Re-enables Periodic Intra Refresh in the H.264 encoder which was (relatively)...

Re-enables Periodic Intra Refresh in the H.264 encoder which was (relatively) recently disabled during updates to the FFmpeg and x264 libraries. Contributed by Benoît Laniel.

src/org/jitsi/impl/neomedia/codec/video/h264/JNIEncoder.java

@@ -501,6 +501,7 @@ else if("h264.profile".equals(k))
                      * FFmpeg will fail.
                      */
                     //"crf" /* constant quality mode, constant ratefactor */, "0",
+                    "intra-refresh", "1",
                     "partitions", "b8x8,i4x4,p8x8",
                     "preset", "ultrafast",
                     "thread_type", "slice",