Notes:

When running a configure script that has nested packages (for example
libcurl's configure with --enable-ares and c-ares sources embedded in
curl tree) and AC_CONFIG_SUBDIRS([nested-subdir]) machinery is used to
automatically run the nested configure script from within the parent
configure script, it happens that the nested _shell_ script will
inherit shell variables exported from the parent _shell_ script.

If for example parent configure script sets and exports LDFLAGS and LIBS
variables with proper values in order to link either a parent library or
program with a library which will be configured and built by a nested
package; It will happen that when the nested configure script runs, the
nested library does not exist yet and _any_ link-test done in the nested
configure will fail, such as those that autoconf macros perform in order
to detect existing compiler and its characteristics, the result is that
the nested configure script will fail with errors such as:

configure: error: C compiler cannot create executables

For now, we no longer export variables previously exported here.

On the other hand, AC_SUBST'ing them is appropriate and even with nested
packages each package's config.status gets its own package values.

So we reinstate AC_SUBST'ing previously AC_SUBST'ed variables.

Fix proper macro expansion order across autotools versions for
C compiler and preprocessor program checks.

Extended the fix from commit 8b15c84e to additionally exclude
pop3_state_apop_resp() if the CURL_DISABLE_CRYPTO_AUTH flag is
defined.

Bug: http://curl.haxx.se/mail/archive-2013-01/0017.html
Reported by: Ulrich Doehner

Reported by: Craig Davison
Bug: http://curl.haxx.se/mail/lib-2013-01/0234.html

Reported by: Craig Davison
Bug: http://curl.haxx.se/mail/lib-2013-01/0234.html

Corrected some function argument definitions to maximize the 80
character line length limit and be in keeping with the curl
coding style.

Fixed an issue where Curl_ssl_connect_nonblocking() wouldn't complete
correctly and the ssldone flag wouldn't be set to true for pop3s based
connections.

Bug introduced in commit: 4ffb8a63.

Added missing imap fix as per commit 709b3506.

Remove internal separated behavior of the easy vs multi intercace.
curl_easy_perform() is now using the multi interface itself.

Several minor multi interface quirks and bugs have been fixed in the
process.

Much help with debugging this has been provided by: Yang Tse

Fixes initial proxy response being processed by the tunneled protocol
handler instead of the HTTP wrapper handler. This issue would trigger
upon delayed CONNECT response from the proxy.

Additionally fixes a multi interface code-path in which connections
would not time out properly.

This does not fix known bug #39.

URL: http://curl.haxx.se/mail/lib-2013-01/0191.html

If the default value for an option taking a long as its value is non
zero, and it is set by zero by a command line option, then that command
line option is not reflected in --libcurl's output. This is because line
520-521 of tool_setopt.c look like:

if(!lval)
    skip = TRUE;

An example of a command-line option doing so is the -k option that sets
CURLOPT_SLL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST to 0L, when the
defaults are non-zero.

Automake documents that doing this will make it choose a different name
for intermediate object files even when sharing source files across
targets of same Makefile.am.

Up to automake 1.13.1 target's intermediate object files were placed
in the build subdirectory of the target. We depended on this, probably
undocumented behavior, to achieve same behavior as if a per-target flag
had been specified when building targets that actually belong to
different Makefile.am files.

It seems automake 1.13.2 is going to break behavior mentioned above.

So, lets use a documented behavior in order to achieve same purpose,
across automake versions, no matter where automake wishes to place
intermediate object files.

Our build targets that already were using a per-target '_CFLAGS' or
'_CPPFLAGS' need no 'fixing', these were already 'fixed'. The only
Makefile.am or Makefile.in files in libcurl's source tree touched by
this 'fix' are tests/libtest/Makefile.inc and tests/unit/Makefile.inc.

Do not use the error messages from NSS for errors not occurring in NSS.

Tested with:

buildconf: autoconf version 2.69
buildconf: autom4te version 2.69
buildconf: autoheader version 2.69
buildconf: automake version 1.13.1
buildconf: aclocal version 1.13.1
buildconf: libtool version 2.4
buildconf: GNU m4 version 1.4.16

... and refresh number of lines of code

It referred to it by the wrong name and said it returned the wrong value.

Reported by: Gisle Vanem

This commit fixes a regression introduced in 052a08ff.

NSS caches certs/keys returned by the SSL_GetClientAuthDataHook callback
and if we connect second time to the same server, the cached cert/key
pair is used.  If we use multiple client certificates for different
paths on the same server, we need to clear the session cache to force
NSS to call the hook again.  The commit 052a08ff prevented the session
cache from being cleared if a client certificate from file was used.

The condition is now fixed to cover both cases: consssl->client_nickname
is not NULL if a client certificate from the NSS database is used and
connssl->obj_clicert is not NULL if a client certificate from file is
used.

Review by: Kai Engert

gcc on DOS hasn't really supported COFF-debug (-gcoff) on djgpp for a
long time.

"Sounds like the COFF debug info generation has bit-rotted in GCC.
 Nothing new here, no other platform uses COFF AFAIK."

So lets drop it too.

URL: http://curl.haxx.se/mail/lib-2013-01/0130.html

This commit renames lib/setup.h to lib/curl_setup.h and
renames lib/setup_once.h to lib/curl_setup_once.h.

Removes the need and usage of a header inclusion guard foreign
to libcurl. [1]

Removes the need and presence of an alarming notice we carried
in old setup_once.h [2]

----------------------------------------

1 - lib/setup_once.h used __SETUP_ONCE_H macro as header inclusion guard
    up to commit ec691ca3 which changed this to HEADER_CURL_SETUP_ONCE_H,
    this single inclusion guard is enough to ensure that inclusion of
    lib/setup_once.h done from lib/setup.h is only done once.

    Additionally lib/setup.h has always used __SETUP_ONCE_H macro to
    protect inclusion of setup_once.h even after commit ec691ca3, this
    was to avoid a circular header inclusion triggered when building a
    c-ares enabled version with c-ares sources available which also has
    a setup_once.h header. Commit ec691ca3 exposes the real nature of
    __SETUP_ONCE_H usage in lib/setup.h, it is a header inclusion guard
    foreign to libcurl belonging to c-ares's setup_once.h

    The renaming this commit does, fixes the circular header inclusion,
    and as such removes the need and usage of a header inclusion guard
    foreign to libcurl. Macro __SETUP_ONCE_H no longer used in libcurl.

2 - Due to the circular interdependency of old lib/setup_once.h and the
    c-ares setup_once.h header, old file lib/setup_once.h has carried
    back from 2006 up to now days an alarming and prominent notice about
    the need of keeping libcurl's and c-ares's setup_once.h in sync.

    Given that this commit fixes the circular interdependency, the need
    and presence of mentioned notice is removed.

    All mentioned interdependencies come back from now old days when
    the c-ares project lived inside a curl subdirectory. This commit
    removes last traces of such fact.

This is a work-around for bug #1180 which is really libcurl's inability
to ignore SIGPIPE in a few cases. With this work-around at least curl
won't suffer from it!

Bug: http://curl.haxx.se/bug/view.cgi?id=1180
Reported by: Lluís Batlle i Rossell