Cleanup: Use correct _WIN32/64 defines for MSVC

Docs: https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros

Differential Revision: https://developer.blender.org/D11460

intern/libmv/libmv/numeric/numeric.h

@@ -43,7 +43,7 @@ inline void sincos(double x, double* sinx, double* cosx) {
 #  endif
 #endif  // !__MINGW64__
 
-#if (defined(WIN32) || defined(WIN64)) && !defined(__MINGW32__)
+#if (defined(_WIN32) || defined(_WIN64)) && !defined(__MINGW32__)
 inline long lround(double d) {
   return (long)(d > 0 ? d + 0.5 : ceil(d - 0.5));
 }