autotools project, which optionally (default=yes) uses libcurl on a system
without a (usable) libcurl installation, but not specifying
`--without-libcurl', configure determines correctly that no libcurl is
available, however, the LIBCURL variable gets expanded to `LIBCURL = -lcurl'
in the resulting Makefiles.
David Shaw fixed the flaw.
the latest features and protocols that libcurl supports and has a minor fix to
better deal with the obscure case where someone has more than one libcurl
installed at the same time.
It now properly handles code that uses curl_free() (since not all versions of
curl have it), and also fixes a few problems when detecting libcurl on MinGW,
and a linker problem on OSX Panther.
