avformat/matroska(dec|enc): Rename macro to avoid clash with winbase.h

winbase.h defines IGNORE and is included via bzlib.h when compiling
for Windows. So rename this macro to NOTHING.
Also rename the muxer macro for consistency.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavformat/matroskadec.c

@@ -2171,8 +2171,8 @@ static int mkv_stereo3d_conv(AVStream *st, MatroskaVideoStereoModeType stereo_mo
     } stereo_mode_conv [] = {
 #define STEREO_MODE_CONV(STEREOMODETYPE, STEREO3DTYPE, FLAGS, WDIV, HDIV, WEBM) \
     [(STEREOMODETYPE)] = { .type = (STEREO3DTYPE), .flags = (FLAGS) },
-#define IGNORE(STEREOMODETYPE, WDIV, HDIV, WEBM)
-        STEREOMODE_STEREO3D_MAPPING(STEREO_MODE_CONV, IGNORE)
+#define NOTHING(STEREOMODETYPE, WDIV, HDIV, WEBM)
+        STEREOMODE_STEREO3D_MAPPING(STEREO_MODE_CONV, NOTHING)
     };
     AVStereo3D *stereo;
     int ret;

libavformat/matroskaenc.c

@@ -1633,9 +1633,9 @@ static int mkv_write_stereo_mode(AVFormatContext *s, EbmlWriter *writer,
          * values to be in the range 0..254. */
 #define STEREOMODE(STEREOMODETYPE, STEREO3DTYPE, FLAGS, WDIV, HDIV, WEBM) \
     [(STEREO3DTYPE)][!!((FLAGS) & AV_STEREO3D_FLAG_INVERT)] = (STEREOMODETYPE) + 1,
-#define IGNORE(STEREOMODETYPE, WDIV, HDIV, WEBM)
+#define NOTHING(STEREOMODETYPE, WDIV, HDIV, WEBM)
         static const unsigned char conversion_table[][2] = {
-            STEREOMODE_STEREO3D_MAPPING(STEREOMODE, IGNORE)
+            STEREOMODE_STEREO3D_MAPPING(STEREOMODE, NOTHING)
         };
         int fmt;