configure: Add missing libavutil inter-library dependencies to .pc files.

This unbreaks static compilation when using pkg-config.
Based on an mplayer2 patch by Uoti Urpala <uau@mplayer2.org>
Signed-off-by: Diego Biurrun <diego@biurrun.de>

configure

@@ -3428,9 +3428,9 @@ EOF
 }
 
 pkgconfig_generate libavutil "Libav utility library" "$LIBAVUTIL_VERSION"
-pkgconfig_generate libavcodec "Libav codec library" "$LIBAVCODEC_VERSION" "$extralibs"
+pkgconfig_generate libavcodec "Libav codec library" "$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" "$extralibs"
-pkgconfig_generate libpostproc "Libav post processing library" "$LIBPOSTPROC_VERSION"
+pkgconfig_generate libpostproc "Libav post processing library" "$LIBPOSTPROC_VERSION" "" "libavutil = $LIBAVUTIL_VERSION"
 pkgconfig_generate libswscale "Libav image rescaling library" "$LIBSWSCALE_VERSION" "" "libavutil = $LIBAVUTIL_VERSION"