php7: enable filter support by default (fixes#3831)
Filter support brings several useful features which many PHP applications
rely on. To make it easier for users who don't want to build own packages
enable this by default. This slightly increases the binary SAPI packages,
but since PHP is a huge monster anyway, I doubt this hurts anybody.
Signed-off-by: Michael Heimpold <mhei@heimpold.de>