Add an entry for the avfilter_get_video_buffer() API change operated

in r20272.

Originally committed as revision 20273 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/APIchanges

@@ -3,7 +3,7 @@ the last major version increase.
 The last version increases were:
 libavcodec:  ?
 libavdevice: ?
-libavfilter: ?
+libavfilter: 2009-10-18
 libavformat: ?
 libpostproc: ?
 libswscale:  ?
@@ -12,6 +12,10 @@ libavutil:   2009-03-08
 
 API changes, most recent first:
 
+2009-10-18 - r20272 - lavfi 1.0.0 - avfilter_get_video_buffer()
+  Make avfilter_get_video_buffer() recursive and add the w and h
+  parameters to it.
+
 2009-10-07 - r20189 - lavfi 0.5.1 - AVFilterPic
   Added w and h fields to AVFilterPic.