Make av_log_level static at next lavu major version bump.

Originally committed as revision 20721 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/log.c

@@ -27,6 +27,9 @@
 #include "avutil.h"
 #include "log.h"
 
+#if LIBAVUTIL_VERSION_MAJOR > 50
+static
+#endif
 int av_log_level = AV_LOG_INFO;
 
 void av_log_default_callback(void* ptr, int level, const char* fmt, va_list vl)