print a warning if something allocates 0 bytes

Originally committed as revision 1307 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/utils.c

@@ -23,6 +23,9 @@
 void *av_mallocz(unsigned int size)
 {
     void *ptr;
+    
+    if(size == 0) fprintf(stderr, "Warning, allocating 0 bytes\n");
+    
     ptr = av_malloc(size);
     if (!ptr)
         return NULL;