configure: Do not add extralibs to avresample .pc file

The library does not have external dependencies.

configure

@@ -4758,5 +4758,5 @@ pkgconfig_generate libavcodec    "Libav codec library"            "$LIBAVCODEC_V
 pkgconfig_generate libavformat   "Libav container format library" "$LIBAVFORMAT_VERSION"   "$extralibs"
 pkgconfig_generate libavdevice   "Libav device handling library"  "$LIBAVDEVICE_VERSION"   "$extralibs"
 pkgconfig_generate libavfilter   "Libav video filtering library"  "$LIBAVFILTER_VERSION"   "$extralibs"
-pkgconfig_generate libavresample "Libav audio resampling library" "$LIBAVRESAMPLE_VERSION" "$extralibs"
+pkgconfig_generate libavresample "Libav audio resampling library" "$LIBAVRESAMPLE_VERSION" "$LIBM"
 pkgconfig_generate libswscale    "Libav image rescaling library"  "$LIBSWSCALE_VERSION"    "$LIBM"