Fix for PR #474: mmreg.h: WAVE_FORMAT_POLYCOM_G729_A identifier missing underscore

(cherry picked from commit 4ae0f392642b79d7f3d38a8376c17aaac80a33d0)
diff --git a/mingw-w64-headers/include/mmreg.h b/mingw-w64-headers/include/mmreg.h
index 953f78b..c7ddc89 100644
--- a/mingw-w64-headers/include/mmreg.h
+++ b/mingw-w64-headers/include/mmreg.h
@@ -2038,7 +2038,7 @@
 #define WAVE_FORMAT_GSM_ADAPTIVE_MULTIRATE_WB 0xa111
 #define WAVE_FORMAT_POLYCOM_G722 0xa112
 #define WAVE_FORMAT_POLYCOM_G728 0xa113
-#define WAVE_FORMAT_POLYCOM G729_A 0xa114
+#define WAVE_FORMAT_POLYCOM_G729_A 0xa114
 #define WAVE_FORMAT_POLYCOM_SIREN 0xa115
 #define WAVE_FORMAT_GLOBAL_IP_ILBC 0xa116
 #define WAVE_FORMAT_RADIOTIME_TIME_SHIFT_RADIO 0xa117