pcre dependencies on php-5.2.2+

It looks like pcre header files were not being installed for us prior to php-5.2.2 when compiled against the non-bundled library.

http://pecl.php.net/bugs/bug.php?id=15968&thanks=1

Do we want to try and hack-up the code further to support php-5.2.2 or should we just make a hard dependency on this?  Alternatively we could add an option to disable pcre support in APC so it would compile,  or they can recomplie older versions with the bundled pcre libraries to get APC working.  I'm not a big fan of trying to get the broken installs to work with APC, as it'll just make things more complicated and hold us back on more useful features.   Thoughts?

-shire