avcodec/h264: call flush_change() on init

This ensures that all the non zero fields get setup correctly.
Alternatively their initialization could be duplicated.

Fixes Ticket2738
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/h264.c

@@ -50,6 +50,8 @@
 
 #include <assert.h>
 
+static void flush_change(H264Context *h);
+
 const uint16_t ff_h264_mb_sizes[4] = { 256, 384, 512, 768 };
 
 static const uint8_t rem6[QP_MAX_NUM + 1] = {
@@ -1633,6 +1635,8 @@ av_cold int ff_h264_decode_init(AVCodecContext *avctx)
 
     avctx->internal->allocate_progress = 1;
 
+    flush_change(h);
+
     return 0;
 }