Even if deprecated, document it so that people will find it as old
scripts may still use it.

The code said "telnet-options" but no documentation ever said so. It
worked fine since the code is fine with a unique match of the first
part.

It has been deprecated and undocumented since commit ad5ead8b (Dec
2003). --ftp-port is the proper long option name.

To make the aliases list reflect reality.

... moved around options so that parsing the code to find all
single-letter options easier.

Bug: https://curl.haxx.se/mail/lib-2016-04/0126.html
Reported-by: Bru Rom

- checks that each option has its own man page present

- checks that each option is mentioned in its corresponding index man
  page

... although it is deprecated.

This also fixes PolarSSL session resume.

Prior to this change the TLS session information wasn't properly
saved and restored for PolarSSL and mbedTLS.

Bug: https://curl.haxx.se/mail/lib-2016-01/0070.html
Reported-by: Thomas Glanzmann

Bug: https://curl.haxx.se/mail/lib-2016-04/0095.html
Reported-by: Moti Avrahami

Fixes #779

OpenSSL 1.1.0-pre seems to return NULL(?) for a whole lot of those
numbers so make sure the function handles this.

Reported-by: Linus Nordberg

Previously, connections were closed immediately before the user had a
chance to extract the socket when the proxy required Negotiate
authentication.

This regression was brought in with the security fix in commit
79b9d5f1

Closes #655

Closes #716

While being debated (in #716) and a violation of RFC 7230 section 5.4,
this test verifies that the existing functionality works as intended. It
strips the dot from the host name and uses the host without dot
throughout the internals.

Regression introduced in 09b5a998

Bug: https://curl.haxx.se/mail/lib-2016-04/0084.html
Reported-by: BoBo

follow-up commit to 3c1e84f5 as it made curl try a little harder

If buffer is allocated, but nothing is received during prereceive
stage, than number of processed bytes must be zero.

Closes #778

Closes #686 for now.

Adding support for IRIs is a mouthful, but is probably interesting at
least for areas and countries where the use of such "URLs" are growing
popularity.

Closes #776

It got too annoying to type =)

The underlying libcurl option used for this feature is
CURLOPT_FTP_CREATE_MISSING_DIRS which has the ability to retry the dir
creation, but it was never set to do that by the command line tool.

Now it does.

Bug: https://curl.haxx.se/mail/archive-2016-04/0021.html
Reported-by: John Wanghui
Help-by: Leif W

Add WITH_MBEDTLS option. Make WITH_SSL, WITH_MBEDTLS and ENABLE_WINSSL
options mutual exclusive.

Closes #606

As of commit d9f3b365

These configure vars are modified in a curl-specific way but never
evaluated or loaded from cache, even though they are designated as
_cv_. We could either implement proper AC_CACHE_CHECKs for them, or
remove them completely.

Fixes #603 as ac_cv_func_gethostbyname is no longer clobbered, and
AC_CHECK_FUNC(gethostbyname...) will no longer spuriously succeed after
the first configure run with caching.

`ac_cv_func_strcasecmp` is curious, see #770.

`eval "ac_cv_func_$func=yes"` can still cause problems as it works in
tandem with AC_CHECK_FUNCS and then potentially modifies its result. It
would be best to rewrite this test to use a new CURL_CHECK_FUNCS macro,
which works the same as AC_CHECK_FUNCS but relies on caching the values
of curl_cv_func_* variables, without modifiying ac_cv_func_*.

These configure vars are modified in a curl-specific way and modified by
the configure process, but are never loaded from cache, even though they
are designated as _cv_. We should implement proper AC_CACHE_CHECKs for
them eventually.

This variable must not be cached in its current form, as any cached
information will prevent the next configure run from determining the
correct LIBS needed for the function. Thus, rename prefix `ac_cv_` to
just `curl_`.