getaddrinfo() implementation.

These minor changes remove portability issues with the this example and allow
it to run on Win32. Specifically:

* The use of pthread_create() has been replaced by g_thread_create(). This
removes the dependency on the pthreads library. Since this is an example using
GTK+, g_thread_create() is available as it is a part of glibc.

* The CURLOPT_FILE option is now referred to by its "newer name"
CURLOPT_WRITEDATA.

* The use of CURLOPT_WRITEFUNCTION has been added.  As described in the docs,
this avoids the crashes when using a DLL under Win32.

* The output file has been renamed from "/tmp/test.curl" to "test.curl". It's
unlikely that there is a /tmp when in Win32 and other examples in libcurl
write their output files to the working directory.

for finding it using mingw on windows.
I also made the script skip the search for gethostbyname_r and gethostbyaddr_r
when ipv6 is enabled.

here.

following a location. After discussions with Tim Baker.

we avoid it where possible.

The standards don't actually allow typecasts between data and functions so
some picky compilers warn about this.

We really don't care, and so many other things could've changed to make the
new test interesting anyway.

both the lib and the header present for both defines to be set. If only one
of the files is found, we issue a warning and set no define.

chunky coding of uploads

chunked transfer-encoding disabled. Fixed to work after Len Krause's
bug report.

to prevent the warning in mprintf.c:

(currently line 930) "format not a string literal, argument types not checked"

picky compiler warnings

PORT
Provide better error messages to allow debugging if one if the ipv6-related
name functions fail in the ftp_use_port() function. This might help us
diagnose the problems on AIX. Also make sure getaddrinfo() uses NULL and
not "0" for the service argument.

as then we include the memdebug.h header from the lib dir, and it then
requires this type... (fails on IRIX 6.5 without this)

about it shadowing the function sin()

added prototypes for the strcasecmp() functions

that assume them to be unsigned. Stops compiler warnings.

warnings