fix closed gop flag

Originally committed as revision 5460 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -330,7 +330,7 @@ extern int motion_estimation_method;
 #define CODEC_FLAG_H263P_SLICE_STRUCT 0x10000000
 #define CODEC_FLAG_INTERLACED_ME  0x20000000 ///< interlaced motion estimation
 #define CODEC_FLAG_SVCD_SCAN_OFFSET 0x40000000 ///< will reserve space for SVCD scan offset user data
-#define CODEC_FLAG_CLOSED_GOP     0x80000000
+#define CODEC_FLAG_CLOSED_GOP     ((int)0x80000000)
 #define CODEC_FLAG2_FAST          0x00000001 ///< allow non spec compliant speedup tricks
 #define CODEC_FLAG2_STRICT_GOP    0x00000002 ///< strictly enforce GOP size
 #define CODEC_FLAG2_NO_OUTPUT     0x00000004 ///< skip bitstream encoding