The Mersenne Twister PRNG was removed, mention replacement.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@18183 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

doc/APIchanges

@@ -12,6 +12,12 @@ libavutil:   2009-03-08
 
 API changes, most recent first:
 
+2009-03-21 - r18116 - lavu 50.2.0  - av_random*
+  The Mersenne Twister PRNG implemented through the av_random* functions
+  was removed. Use the lagged Fibonacci PRNG through the av_lfg* functions
+  instead.
+
+
 2009-03-08 - r17869 - lavu 50.0.0  - AVFifoBuffer
   av_fifo_init, av_fifo_read, av_fifo_write and av_fifo_realloc were dropped
   and replaced by av_fifo_alloc, av_fifo_generic_read, av_fifo_generic_write