Allow (*curl_write_callback) write callbacks to return
CURL_WRITEFUNC_OUT_OF_MEMORY to properly indicate libcurl of OOM conditions
inside the callback itself.

If a socket is larger than FD_SETSIZE, avoid using FD_SET() on the
platforms where this is possible.

Bug: http://curl.haxx.se/bug/view.cgi?id=3413274
Reported by: Tim Starling

When we use binary posts and regular ones intermixed on a single command
line, we cannot do strlen() etc on the data to figure out the length
(when inserting '&' and more). We must therefore keep track of the post
data length. Then we also end up setting the libcurl option with the
known size, so that we don't risk that libcurl will do strlen() on the
data.

This has the minor side-effect that --libcurl source codes now always
will use CURLOPT_POSTFIELDSIZE but I don't consider that terribly
damaging.

Bug: http://curl.haxx.se/bug/view.cgi?id=3413181
Reported by: Taneli Vähäkangas

Probably the wrong place, but I dont know better.

In some cases Content-Length: couldn't be replaced by an application

Also, indented some code properly

To avoid that the progress meter headers get output between each
transfer, make sure the bits gets kept when (re-)inited.

Reported by: Christopher Stone

my_setopt and my_setopt_str no longer ignores curl_easy_setopt result.

Fixed some OOM handling issues.

Verifies the fix from commit 322f3d5a

I think curl should ignore this case and smtp.c should test for this.
Since RFC-2821 seems to allow a "null reverse-path". Ref.  "MAIL
FROM:<>" in section 3.7, page 25.

Example:
* upload completely sent off: 35out of 35 bytes

Should be:
* upload completely sent off: 35 out of 35 bytes

Related code not ready yet for this kind of checks.

Suffix rules cannot have any prerequisites of their own.

Added envvars to specify OpenSSL include, libpath and lib.
Added rule to create curlbuild.h from curlbuild.h.dist.

my_setopt and my_setopt_str no longer ignores curl_easy_setopt result.

Fixed some OOM handling issues.

Overhauled FindWin32CACert()

All paths to dependencies now quoted; synced examples makefile.

Also added check for __x86_64__ define since MinGW64 seems to define
the _M_X64 macro through a header not available for config-win32.h.

Fix posted by Tomas Hoger <thoger redhat com>.