This patch cleans up the automatically-generated (?) code and fixes one
case that will always fail due to syntax error.

HAVE_GETHOSTBYADDR_R_5_REENTRANT always failed because of a trailing
character ("int length;q"). Several parameter type and unused variable
warnings popped up. This causes a detection failure with -Werror.

Observe that the REENTRANT cases are exactly the same as their
non-REENTRANT cases except for a `_REENTRANT` macro definition.
Merge all these pieces and build one big main function with different
cases, but reusing variables where logical.

For the cases where the parameters where NULL, I looked at
lib/hostip4.c to get an idea of the parameters types.

void-cast variables such as 'rc' to avoid -Wuninitialized errors.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>

autotools does not use features.h nor _BSD_SOURCE. As this macro
triggers warnings since glibc 2.20, remove it. It should not have
functional differences.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>

Additionally, updated "GSSAPI" to "GSS-API" for a Cmake related change
as GSSAPI can be confused with the authentication mechanism rather than
a GSS-API implementation library such as MIT or Heimdal.

Added support for WinIDN build configurations to the VC6 project files.

Added support for WinIDN build configurations to the VC7 and VC7.1
project files.

A left over from the VC6 project files, so mainly cosmetic in Visual
Studio .NET as it can handle both comma and semi-colon characters for
separating multiple pre-processor definitions.

However, the IDE uses semi-colons if the value is edited, and as such,
this may cause problems in future for anyone updating the files or
merging patches.

Used the Visual Studio IDE to correct the separator character.

..when working from the git repository. This is particularly useful
for single development environments where the project files for all
supported versions of Visual Studio may not be required.

Prior to this change if x64 release was specified a failed attempt was
made to build x86 release instead.

...and removed duplication of what protocols are supported from the
description text.

...and revised the proxy wording a little as well.

...and corrected a related typo in curl_easy_setopt.3.

As this has been present for SOCKSv5 proxy since v7.19.4 and for IMAP,
POP3 and SMTP authentication since v7.38.0.

Support for Kerberos V4 was removed in v7.33.0.

Typically the USE_WINDOWS_SSPI definition would not be used when the
CURL_DISABLE_CRYPTO_AUTH define is, however, it is still a valid build
configuration and, as such, the SASL Kerberos V5 (GSSAPI) authentication
data structures and functions would incorrectly be used when they
shouldn't be.

Introduced a new USE_KRB5 definition that takes into account the use of
CURL_DISABLE_CRYPTO_AUTH like USE_SPNEGO and USE_NTLM do.

More CURLcode fixes.

Basically since servers often then don't respond well to this and
instead send the full contents and then libcurl would instead error out
with the assumption that the server doesn't support resume. As the data
is then already transfered, this is now considered fine.

Test case 1434 added to verify this. Test case 1042 slightly modified.

Reported-by: hugo
Bug: http://curl.haxx.se/bug/view.cgi?id=1443

More standardisation of CURLcode usage and coding style.

...and some minor code style changes.

As this is covered by the PROTOCOLS section and saves having to update
two parts of the document with the same information in future.

As implementations are refereed to GSS-API libraries as per the RFC and
GSSAPI typically refers to an authentication mechanism.

Added missing IMAP to the protocol list.

...as this option affects more that just FTP.

Whilst the description included information about SMTP, the protocol
list only showed "TTP, FTP, IMAP, POP3".

... and allow building with nghttp2 but completely without NPN and ALPN,
as nghttp2 can still be used for plain-text HTTP.

Reported-by: Lucas Pardue

... since the conditional in the code are now based on OpenSSL versions
instead to better support non-configure builds.

conversion from 'size_t' to 'unsigned int', possible loss of data

Return a more appropriate error, rather than CURLE_OUT_OF_MEMORY when
acquiring the credentials handle fails. This is then consistent with
the code prior to commit f7e24683 when log-in credentials were empty.