Fix _MSC_VER check

Use "#if defined(_MSC_VER)" instead of "#if _MSC_VER" to be consistent with other usages in the file and to work with the "-Wundef" warning.

PiperOrigin-RevId: 499471290
Change-Id: I34a9442eecf266afd74d4332cab7d39766df4ed9

googletest/include/gtest/internal/gtest-port.h

@@ -2142,7 +2142,7 @@ GTEST_DISABLE_MSC_DEPRECATED_POP_()
 // MSVC-based platforms.  We map the GTEST_SNPRINTF_ macro to the appropriate
 // function in order to achieve that.  We use macro definition here because
 // snprintf is a variadic function.
-#if _MSC_VER && !GTEST_OS_WINDOWS_MOBILE
+#if defined(_MSC_VER) && !GTEST_OS_WINDOWS_MOBILE
 // MSVC 2005 and above support variadic macros.
 #define GTEST_SNPRINTF_(buffer, size, format, ...) \
   _snprintf_s(buffer, size, size, format, __VA_ARGS__)