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.
Enabled PDO and PDO_SQLITE by default.
Fixup PDO header detection so that it searches in the correct order, and
correctly picks up the headers when building from outside of the source
tree.
TODO: make pdo_XXX auto-enable when XXX is enabled. Volunteers welcome.