Use enum CodecID instead of int.

Fixes the following icc warning:
warning #188: enumerated type mixed with another type

Originally committed as revision 19340 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffmpeg.c

@@ -3051,7 +3051,7 @@ static void new_video_stream(AVFormatContext *oc)
 {
     AVStream *st;
     AVCodecContext *video_enc;
-    int codec_id;
+    enum CodecID codec_id;
 
     st = av_new_stream(oc, oc->nb_streams);
     if (!st) {
@@ -3193,7 +3193,7 @@ static void new_audio_stream(AVFormatContext *oc)
 {
     AVStream *st;
     AVCodecContext *audio_enc;
-    int codec_id;
+    enum CodecID codec_id;
 
     st = av_new_stream(oc, oc->nb_streams);
     if (!st) {