Add an entry for the AVFilterBuffer change of r24592.

Originally committed as revision 24593 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/APIchanges

@@ -13,6 +13,12 @@ libavutil:   2009-03-08
 
 API changes, most recent first:
 
+2010-07-30 - r24592 - lavfi 1.27.0 - AVFilterBuffer
+  Increase size of the arrays AVFilterBuffer.data and
+  AVFilterBuffer.linesize from 4 to 8.
+
+  This change breaks libavfilter ABI.
+
 2010-07-29 - r24583 - lavcore 0.2.0 - imgutils.h
   Add functions av_fill_image_linesizes() and
   av_fill_image_pointers(), declared in libavcore/imgutils.h.