file_disconnect() free's resources for multi API

Additionally, improved error checking and logging.

Multiple auths in the same WWW-Authenticate header

Fixed in commit 7d81e3f7193b8c

The fix is pretty much the one Nick Zitzmann provided, just edited to do
the right indent levels and with test case 1204 added to verify the fix.

Bug: http://curl.haxx.se/mail/lib-2011-10/0190.html
Reported by: Nick Zitzmann

Fix a bug with with commit 2621dd42 that happened due to my last
second pre-commit cleanup of the change without proper testing
afterwards!

This return code has not been used since 7.20.0 so we can stop
mentioning it for current libcurl.

The default lowat level for gnutls-2.12* is set to zero to avoid
unnecessary system calls and the gnutls_transport_set_lowat function has
been totally removed in >=gnutls-3 which causes build failures.

Therefore, the function shouldn't be used except for versions that
require it, <gnutls-2.12.0.

As the EOB string can come byte by byte over a series of writes we must
match byte-wise.

Bug: http://curl.haxx.se/mail/lib-2011-10/0172.html

Previously the bit was set before the connection was found working so if
it would first fail to an ipv6 address and then connect fine to a IPv4
address the variable would still be TRUE.

Reported by: Thomas L. Shinnick
Bug: http://curl.haxx.se/bug/view.cgi?id=3421912

Bug: https://bugzilla.redhat.com/733685

Do not use artificial nicknames for certificates from files.

... instead of nicknames, which are not unique.

Reported by: Thomas L. Shinnick

Previously we required that -S/--show-error was used _after_
-s/--silent. This was slightly confusing since we strive to make
arguments as position independent as possible.

Now, you can use them in any order and the result should still be the
same.

Bug: http://curl.haxx.se/bug/view.cgi?id=3424286
Reported by: Andreas Olsson

Elaborate what max_fd == -1 means

Remove the reference to CURLM_CALL_MULTI_PERFORM as modern libcurl
versions don't ever return that.

When doing a multipart formpost with a read callback, and that callback
returns CURL_READFUNC_ABORT, that return code must be properly
propagated back and handled accordingly. Previously it would be handled
as a zero byte read which would cause a hang!

Added test case 587 to verify. It uses the lib554.c source code with a
small ifdef.

Reported by: Anton Bychkov
Bug: http://curl.haxx.se/mail/lib-2011-10/0097.html

There might be situations where a user would want to unset this option.
Avoid forcing him/her to cast the NULL argument to (char *) in order to
get past the compile time typecheck.

Save the errno value immediately after a connect() failure so that it
won't get reset to something else before we read it.

Bug: http://curl.haxx.se/mail/lib-2011-10/0066.html
Reported by: Frank Van Uffelen and Fabian Hiernaux

Jerry Wu detected and provided detailed info about this issue.

When, for a given test, server is instructed to close connection after
server reply we now wait a very small amount of time (50ms) before doing
so. This is done to allow client to, at least partially, read server
reply before getting an ECONNRESET.

The above is required to make test cases 1070, 1200, 1201 and 1202 pass
with Cygwin 1.5.X on W2K.

GOPHER test server closes connection after _every_ server-reply, as such,
at some point it could require a bigger time or using shutdown() before
a server-side initiated disconnection.

both introduced in 42be24af

Set ACK timeout to 5 seconds.

If we are waiting for block X and receive block Y that is the expected one, we
should send ACK and increase X (which is already implemented). Otherwise drop
the packet and don't increase retry counter.

Prevent modification of easy handle being added with curl_multi_add_handle()
unless this function actually suceeds.

Run Curl_posttransfer() to allow restoring of SIGPIPE handler when
Curl_connect() fails early in multi_runsingle().