configure: add dependencies to lavfi .pc file

The scale filter depends on sws, resample on lavr, and movie on lavf and
lavc.

Fixes Bug 502.

configure

@@ -4165,10 +4165,15 @@ Cflags: -I\${includedir}
 EOF
 }
 
+lavfi_libs="libavutil = $LIBAVUTIL_VERSION"
+enabled movie_filter    && prepend lavfi_libs "libavformat >= $LIBAVFORMAT_VERSION, libavcodec >= $LIBAVCODEC_VERSION,"
+enabled resample_filter && prepend lavfi_libs "libavresample >= $LIBAVRESAMPLE_VERSION,"
+enabled scale_filter    && prepend lavfi_libs "libswscale >= $LIBSWSCALE_VERSION,"
+
 pkgconfig_generate libavutil "Libav utility library" "$LIBAVUTIL_VERSION" "$LIBM"
 pkgconfig_generate libavcodec "Libav codec library" "$LIBAVCODEC_VERSION" "$extralibs" "libavutil = $LIBAVUTIL_VERSION"
 pkgconfig_generate libavformat "Libav container format library" "$LIBAVFORMAT_VERSION" "$extralibs" "libavcodec = $LIBAVCODEC_VERSION"
 pkgconfig_generate libavdevice "Libav device handling library" "$LIBAVDEVICE_VERSION" "$extralibs" "libavformat = $LIBAVFORMAT_VERSION"
-pkgconfig_generate libavfilter "Libav video filtering library" "$LIBAVFILTER_VERSION" "$extralibs" "libavutil = $LIBAVUTIL_VERSION"
+pkgconfig_generate libavfilter "Libav video filtering library" "$LIBAVFILTER_VERSION" "$extralibs" "$lavfi_libs"
 pkgconfig_generate libavresample "Libav audio resampling library" "$LIBAVRESAMPLE_VERSION" "$extralibs" "libavutil = $LIBAVUTIL_VERSION"
 pkgconfig_generate libswscale "Libav image rescaling library" "$LIBSWSCALE_VERSION" "$LIBM" "libavutil = $LIBAVUTIL_VERSION"