avformat/movenc-test: Make format static

Makes greping for non static consts easier
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/movenc-test.c

@@ -44,7 +44,7 @@ static const uint8_t aac_extradata[] = {
 };
 
 
-const char *format = "mp4";
+static const char *format = "mp4";
 AVFormatContext *ctx;
 uint8_t iobuf[32768];
 AVDictionary *opts;