Merge commit 'd1a6cb19'

* commit 'd1a6cb19':
  x86: Serialize rdtsc in read_time()
Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/x86/timer.h

@@ -31,7 +31,12 @@
 static inline uint64_t read_time(void)
 {
     uint32_t a, d;
-    __asm__ volatile("rdtsc" : "=a" (a), "=d" (d));
+    __asm__ volatile(
+#if ARCH_X86_64 || defined(__SSE2__)
+                     "lfence \n\t"
+#endif
+                     "rdtsc  \n\t"
+                     : "=a" (a), "=d" (d));
     return ((uint64_t)d << 32) + a;
 }