Bug 1412240 part 1: Add a preemptive stdlib.h include in our libavutil_visibility.h hackaround file. r=jya

MozReview-Commit-ID: 8nmOy2aqPA0

--HG--
extra : rebase_source : 485e205af8fbb205c81929e12eac00410570124d

media/ffvpx/libavutil_visibility.h

@@ -9,6 +9,16 @@
 #ifndef MOZILLA_AVUTIL_VISIBILITY_H
 #define MOZILLA_AVUTIL_VISIBILITY_H
 
+// We need to preemptively include <stdlib.h> before anyone[1] has a chance
+// to include <limits.h>. We do this to avoid a linux clang build error, in
+// -ffreestanding mode on automation, which happens when limits.h defines
+// MB_LEN_MAX to some value that is different from what stdlib.h expects. If
+// we include stdlib.h before limits.h, then they don't get a chance to
+// interact badly.
+//
+// [1] (e.g. libavutil/common.h, which is indirectly included by log.h below.)
+#include <stdlib.h>
+
 #pragma GCC visibility push(default)
 #include "libavutil/cpu.h"