an alloc func failing should give ENOMEM anyway.

Originally committed as revision 7737 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/framehook.c

@@ -57,7 +57,7 @@ int frame_hook_add(int argc, char *argv[])
 
     fhe = av_mallocz(sizeof(*fhe));
     if (!fhe) {
-        return errno;
+        return -ENOMEM;
     }
 
     fhe->Configure = dlsym(loaded, "Configure");