Remove disabled code - threaded fetching. This can be implemented
on a upper level and by offloading it we reduce the complexity of
the core.

Compressed protocol support + extensibility for mysqlnd

- Fix the build issue with php_mysqlnd_config.h ending up in wrong build directory

Check for the different types and create the
corresponding configuration file, so it can be used
by mysqli, even if mysqlnd is not enabled at all.

The experimental warning sohuld be in the configure output...

- mark mysqlnd's threading (which can be used for background pre-fetching)
experimental

MFB

Update mysqlnd, ext/mysql and ext/mysqli - now possible to compile with different
configurations one or the another extension to use libmysql or mysqlnd mixed in
one binary

Fix the build, add a missing file

Moving extension specific code to php_mysqlnd.c as the old rule is.

MFB:
some config.w32 fixes
moved mysqlnd's block allocator to a separate file and also now
it's part of the connection, no MT problems.

Update mysqlnd in HEAD
Updated ext/mysql and ext/mysqli in HEAD

- Check also if ulong is available

- Moved mysqnd to it's own directory: It is sort of an extension itself.
(Similar to what ext/libxml is..)