odintrin: avoid redef of M_* under visual studio

math.h provides these with _USE_MATH_DEFINES

BUG=aomedia:500

Change-Id: I6e05b09149a6a6ca152e67194b629e0728bc3c35

av1/common/odintrin.h

diff --git a/av1/common/odintrin.h b/av1/common/odintrin.h
index fe99d80..3a778ab 100644
--- a/av1/common/odintrin.h
+++ b/av1/common/odintrin.h
@@ -14,6 +14,9 @@
 #ifndef AV1_COMMON_ODINTRIN_H_
 #define AV1_COMMON_ODINTRIN_H_
 
+#if defined(_MSC_VER)
+# define _USE_MATH_DEFINES
+#endif
 #include <math.h>
 #include <stdlib.h>
 #include <string.h>