Previously, we unconditionally ignored any plugins whose names ended
with _debug.dylib. This makes the mediaservice plugins unusable on Mac
if Qt is configured to build plugins as debug-only (which is
incidentally the default).
Change-Id: I5a8981b2251e803fa233b74c968f6eaa452d367c
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>