ET_HAS_EXCEPTIONS: require defined(_MSC_VER) to conclude _HAS_EXCEPTIONS implies exceptions are on

Differential Revision: D76857541

Pull Request resolved: #11770

Author: swolchok

runtime/platform/compiler.h

@@ -173,7 +173,7 @@ using ssize_t = ptrdiff_t;
 
 #ifdef __EXCEPTIONS
 #define ET_HAS_EXCEPTIONS 1
-#elif defined(_HAS_EXCEPTIONS) && _HAS_EXCEPTIONS
+#elif defined(_MSC_VER) && defined(_HAS_EXCEPTIONS) && _HAS_EXCEPTIONS
 #define ET_HAS_EXCEPTIONS 1
 #else
 #define ET_HAS_EXCEPTIONS 0