Make avcodec_check_dimensions() return AVERROR(EINVAL) rather than -1

in case of invalid picture size.

Originally committed as revision 22962 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/utils.c

@@ -224,7 +224,7 @@ int avcodec_check_dimensions(void *av_log_ctx, unsigned int w, unsigned int h){
         return 0;
 
     av_log(av_log_ctx, AV_LOG_ERROR, "picture size invalid (%ux%u)\n", w, h);
-    return -1;
+    return AVERROR(EINVAL);
 }
 
 int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic){