session_pgsql module commit notice

Hi all, This is the last notice before PostgreSQL session save handler module commit. I've renamed it to session_pgsql so that users will understand it's a sub module for session module. I've also changed Makefile.in so that php_session.h is installed. Other headers will be installed. If you care, nobody will object to change it(?) _php_find_ps_module() call should be moved to avoid httpd start up time error message and make external session save handler to work correctly. I'll commit the fix also. (It's *not* a real solution, but it must be addressed now. There are a few bug reports for this already) -- Yasuo Ohgaki