Add av_uninit macro to variable to avoid false positive warning:

libavformat/electronicarts.c: In function ‘ea_read_packet’:
libavformat/electronicarts.c:447: warning: ‘num_samples’ may be used uninitialized in this function

Originally committed as revision 17157 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/electronicarts.c

@@ -444,7 +444,7 @@ static int ea_read_packet(AVFormatContext *s,
     int packet_read = 0;
     unsigned int chunk_type, chunk_size;
     int key = 0;
-    int num_samples;
+    int av_uninit(num_samples);
 
     while (!packet_read) {
         chunk_type = get_le32(pb);