mediastreamer: introduce environment variable to set plugins directory

pkgs/development/libraries/mediastreamer/default.nix

@@ -11,11 +11,12 @@ stdenv.mkDerivation rec {
     sha256 = "1g6gawrlz1lixzs1kzckm3rxc401ww8pi00x7r5kb84bdijb02cc";
   };
 
+  patches = [ ./plugins_dir.patch ];
+
   postPatch = ''
     sed -i "s/\(SRTP_LIBS=\"\$SRTP_LIBS -lsrtp\"\)/SRTP_LIBS=\"$(pkg-config --libs-only-l libsrtp)\"/g" configure
   '';
 
-  # TODO: make it load plugins from *_PLUGIN_PATH
   nativeBuildInputs = [ pkgconfig intltool ];
 
   propagatedBuildInputs = [
@@ -28,6 +29,8 @@ stdenv.mkDerivation rec {
   configureFlags = [
     "--enable-external-ortp"
     "--with-srtp=${srtp}"
+    "--enable-xv"
+    "--enable-glx"
   ];
 
   meta = with stdenv.lib; {