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>.

Expanded the section about CURLOPT_URL to include the format of the URL
and detailed information and examples relating to specific protocols.

Fixed Curl_gethostname() so that it always returns the un-qualified
machine name rather than being dependent on the socket provider.

Note: The return of getenv("CURL_GETHOSTNAME") is also parsed in case
the developer / test harness provided a fully qualified domain name as
it's value as well.

Additionally function my_useragent() now provides default User-Agent string

Reorder handling of fields to match same order as the one given by current
definition order of 'Configurable' struct fields. Fields currently not handled
marked for further inspection.

Reviewing fields being free'd in free_config_fields() still pending

Additionally some code reorganization and direct OOM handling fixes,
just another step towards fixing curl tool issues uncovered 2011-09-15

Additionally fix data type of result vars for iconv() calls

Re-enabling MemoryTracking capability on 'src' subdirectory files and torture
tests have uncovered many issues which were going unnoticed in curl tool. So
here we go fixing some of them. Others still remain and should be addressed
ASAP, given that curl tool is used in our test harness also for test server
start verification purposes. There are even non-socket file descriptor leaks.

Use same preprocessor logic for curl tool MemoryTracking activation in source
files located in 'src' subdirectory as the one used for libcurl sources.

A custom HTTP header ending in a semicolon instead of a colon
will be treated as a header to be added without any data
portion.

With this fix, it should work for PolarSSL-1.0.0 (and SVN-1091 trunk)
and retain compatibility with earlier versions. (Tested with 0.14.1)

PolarSSL still doesn't play nicely with curl's CA bundle (we discussed
this before) but I was at least able to retrieve the
https://www.gmail.com/ login page using a modified ca-certificates.crt
file with all 3 versions of PolarSSL.

Reported by: Jeff Pohlmeyer