Also, added a few hints to help compilers to perform tail call
recursion optimization.

In libssh2 1.2.8, libssh2_session_handshake() replaces
libssh2_session_startup() to fix the previous portability problem with
the socket type that was too small for win64 and thus easily could cause
crashes and more.

It is a bad idea to use the public prefix used by another library and
now we realize that libssh2 introduces a symbol in the upcoming version
1.2.8 that conflicts with our static function named libssh2_free.

When failing to build form post due to an error, the code now does a
proper failf(). Previously libcurl would report an error like "failed
creating formpost data" when a file wasn't possible to open which was
not easy for users to figure out.

I also lower cased a function name to be named more curl-style and
removed some unnecessary code.

The URL parser got a little stricter as it now considers a ? to be a
host name divider so that the slightly sloppier URLs work too. The
problem that made me do this change was the reported problem with an URL
like: www.example.com?email=name@example.com This form of URL is not
really a legal URL (due to the missing slash after the host name) but is
widely accepted by all major browsers and libcurl also already accepted
it, it was just the '@' letter that triggered the problem now.

The side-effect of this change is that now libcurl no longer accepts the
?  letter as part of user-name or password when given in the URL, which
it used to accept (and is tested in test 191). That letter is however
mentioned in RFC3986 to be required to be percent encoded since it is
used as a divider.

Bug: http://curl.haxx.se/bug/view.cgi?id=3090268

It is for FTP, SMTP, POP3, IMAP at least.

"SFTP resume with 4GB file does not work" is now removed as I'm sure
this is really a libssh2 bug and not a libcurl bug.

7.21.2 is released already

Accidentally left in there during my previous debugging of this

In order to avoid for example the pingpong protocols to issue STARTTLS
(or equivalent) even though there's no SSL support built-in.

Reported by: Sune Ahlgren
Bug: http://curl.haxx.se/mail/archive-2010-10/0045.html

Some options, such as the automatic decompression and some SSL related
ones now will bail out if the underlying libcurl doesn't have support
for the particular feature needed.

Reported by: Christian Weisgerber
Bug: http://curl.haxx.se/bug/view.cgi?id=3087479

The option takes a parameter that should be 1 or 0 to enable or disable
the feature.

URL: http://curl.haxx.se/bug/view.cgi?id=3086428

Modified Watcom targets to avoid backslashs so that they can
work on Linux too.

Do not match the trailing '\n' in the regular expression as this would
make us dump a ) parenthesis on a new line.

This fixes the following error:

would get transformed into:

)

Bug: http://curl.haxx.se/mail/lib-2010-10/0065.html
Reported by: Dimitre Dimitrov

If the filename contains a backslash, only use filename portion. The
idea is that even systems that don't handle backslashes as path
separators probably want that path removed for convenience.

This flaw is considered a security problem, see the curl security
vulnerability http://curl.haxx.se/docs/adv_20101013.html

This is similar to how it's done in the lib directory.
The Amiga build appears to have been broken for a year because
of a missing homedir.c

As the change in 5f0ae7a0 added a precaution against negative
file sizes that for some reason managed to get returned, this change now
introduces the same check at the second place in the code where the file
size from the libssh2 stat call is used.

This check might not be suitable for a 32 bit curl_off_t, but libssh2.h
assumes long long to work and to be 64 bit so I believe such a small
curl_off_t will be very unlikely to occur in the wild.

... and some minor source code whitespace edits

Having an open brace without a closing brace caused a segfault.

Having a closing brace too many caused a silent error to occur, which
caused curl to bail out and return an error code but no error message
was shown. It does now!

All error message outputs no longer wrongly get _two_ newlines written
after the error message.

Reported by: Vlad Ureche
Bug: http://curl.haxx.se/bug/view.cgi?id=3083942

The invocation of autoconf's AC_PATH_PROG( ) is not quite right for
finding curl-config. This fix corrects the negative case (where
curl-config is not found).