Make pkgconfig_generate check if the library is enabled before to

generate the pc files.

Originally committed as revision 24519 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -3173,6 +3173,7 @@ comment=$2
 version=$3
 libs=$4
 requires=$5
+enabled $shortname || return
 cat <<EOF > $name/$name.pc
 prefix=$prefix
 exec_prefix=\${prefix}
@@ -3210,8 +3211,6 @@ pkgconfig_generate libavcore "FFmpeg multimedia shared core utilities library" "
 pkgconfig_generate libavcodec "FFmpeg codec library" "$LIBAVCODEC_VERSION" "$extralibs" "libavcore = $LIBAVCORE_VERSION"
 pkgconfig_generate libavformat "FFmpeg container format library" "$LIBAVFORMAT_VERSION" "$extralibs" "libavcodec = $LIBAVCODEC_VERSION"
 pkgconfig_generate libavdevice "FFmpeg device handling library" "$LIBAVDEVICE_VERSION" "$extralibs" "libavformat = $LIBAVFORMAT_VERSION"
-enabled avfilter &&
     pkgconfig_generate libavfilter "FFmpeg video filtering library" "$LIBAVFILTER_VERSION" "$extralibs" "libavcore = $LIBAVCORE_VERSION"
-enabled postproc &&
     pkgconfig_generate libpostproc "FFmpeg post processing library" "$LIBPOSTPROC_VERSION"
 pkgconfig_generate libswscale "FFmpeg image rescaling library" "$LIBSWSCALE_VERSION" "" "libavutil = $LIBAVUTIL_VERSION"