build_sys: Add dependencies for pp testing.

Should fix mp=pp test failure by not running it without --enable-gpl
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -1789,6 +1789,12 @@ test_deps _muxer _demuxer                                               \
 
 ac3_fixed_test_deps="ac3_fixed_encoder ac3_decoder"
 mpg_test_deps="mpeg1system_muxer mpegps_demuxer"
+pp_test_deps="mp_filter"
+pp2_test_deps="mp_filter"
+pp3_test_deps="mp_filter"
+pp4_test_deps="mp_filter"
+pp5_test_deps="mp_filter"
+pp6_test_deps="mp_filter"
 
 # default parameters