Atomic builtins are from in GCC 4.1.0 onward.

We definitely don't want to use the slow mutex or risky spin locks,
unless we have to.

modules/demux/rtpsession.c

@@ -140,6 +140,7 @@ struct rtp_source_t
     uint32_t ssrc;
     uint16_t bad_seq; /* tentatively next expected sequence for resync */
     uint16_t max_seq; /* next expected sequence */
+    uint32_t jitter;  /* interarrival delay jitter estimate */
 
     uint16_t last_seq; /* sequence of the last dequeued packet */
     block_t *blocks; /* re-ordered blocks queue */

src/libvlc.c

@@ -77,7 +77,7 @@
 #endif
 
 #if defined(__GNUC__)
-#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 4)
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
 #define USE_SYNC
 #endif
 #endif