Configure scripts for extensions look for PDO include files in
$prefix/include/php. This change makes them look into $phpincludedir
instead, which may be different from $prefix/include/php.
modern versions in the same build chain. There are
simply too many broken things in 2.13 to make it work.
Cache handling is broken as well which is why I need
to revert the pdo_inc_path cache fix as well.
trunk is now 2.60+ only and I'll work on cleaning out
all the legacy cruft from there.