avformat/flacenc: Add const to ff_flac_write_header() parameter

The extradata is not changed at all.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/flacenc.h

@@ -26,7 +26,7 @@
 #include "libavcodec/bytestream.h"
 #include "avformat.h"
 
-int ff_flac_write_header(AVIOContext *pb, uint8_t *extradata,
+int ff_flac_write_header(AVIOContext *pb, const uint8_t *extradata,
                          int extradata_size, int last_block);
 
 int ff_flac_is_native_layout(uint64_t channel_layout);

libavformat/flacenc_header.c

@@ -26,7 +26,7 @@
 #include "avformat.h"
 #include "flacenc.h"
 
-int ff_flac_write_header(AVIOContext *pb, uint8_t *extradata,
+int ff_flac_write_header(AVIOContext *pb, const uint8_t *extradata,
                          int extradata_size, int last_block)
 {
     uint8_t header[8] = {