getaddrinfo is fully thread safe on solaris versions which
implement the function even when h_errno is not a macro.

The h_errno macro test now only done on systems for which there
is no hard coded knowledge about getaddrinfo's thread safeness.

Remove files generated on previous buildconf/configure run

Remove enable-thread / disable-thread configure option. These were only placebo
options. The library is always built as thread safe as possible on every system.

Refactor how preprocessor symbol _THREAD_SAFE definition is done.

knowledge says the contrary or h_errno is not defined.

- Constantine Sapuntzakis reported that Darwin 6.0 a.k.a. MAC OS X 10.2
  and newer have a threadsafe getaddrinfo.

- Fix Dragonfly BSD triplet detection.

- In case the hard-coded knowledge says that getaddrinfo is threadsafe,
  an additional check is done to verify that h_errno is also defined.
  If h_errno isn't defined, we finally assume that it isn't threadsafe.
  Jamie Lokier provided the inspiration for this extra check.

Add some comments to better understand what the regex's pretend to achieve.

c-ares libraries in debug and release flavours.

Additionally each of the three sample programs is built against
each of the four possible c-ares libraries, generating all this
a total number of 12 executables and 4 libraries.

c-ares with --enable-curldebug uses memdebug.h from libcurl's lib subdirectory.

memdebug.h needs access to libcurl's setup.h from libcurl's lib subdirectory
and also needs access to libcurl's generated curl_config.h

Undo old temporary change once used for testing purposes

Symbol hiding configure options renamed to the hopefully less ambiguous
--enable-symbol-hiding and --disable-symbol-hiding as well as related
macro names and some internal variables used for them.

Related configuration file preprocessor symbols named to
CARES_SYMBOL_HIDING and CARES_SYMBOL_SCOPE_EXTERN.

Fix two typos.

shows that this one is actually a modified copy of ares_parse_a_reply.c.

In order to comply with ares_parse_a_reply.c's M.I.T. license, the old
1998 M.I.T. copyright notice is now also preserved in this file the same
as it is done in other ares_parse_*.c files.

Fix identation of some license lines.

ares_parse_txt_reply() current version:

- Fixed a couple of potential double free's.

- Fixed memory leaks upon out of memory condition.

- Fixed pointer arithmetic.

- Setting ntxtreply to zero upon entry for all failure cases.

- Changed data type to size_t for variables substr_len, str_len and
  the length member of ares_txt_reply struct.

- Avoided a couple of memcpy() calls.

- Changed i data type to unsigned int to prevent compiler warnings.

- Adjusted a comment.

- Use ARES_SUCCESS literal for successfull completion.

- Added CVS Id tag.