make output buffer larger so drift compensation can work

Originally committed as revision 9967 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/resample.c

@@ -191,7 +191,7 @@ int audio_resample(ReSampleContext *s, short *output, short *input, int nb_sampl
     }
 
     /* make some zoom to avoid round pb */
-    lenout= (int)(nb_samples * s->ratio) + 16;
+    lenout= (int)(4*nb_samples * s->ratio) + 16;
     bufout[0]= (short*) av_malloc( lenout * sizeof(short) );
     bufout[1]= (short*) av_malloc( lenout * sizeof(short) );