Enable building php import support if all required dependencies have been found

Building PHP import support requires development packages for
KDevPlatform and kdevelop-PG-Qt and is currently limited to KDE4.

Signed-off-by: Ralf Habacker <ralf.habacker@freenet.de>

BUG:148911
FIXED-IN:2.22.80 (KDE Applications 17.07.80)