Stop testing on COMPILER_MSVC.  The correct choice is _WIN32.
See:
RELNOTES: None
@@ -82,7 +82,7 @@ EOF
int main(void)
{
-#ifdef COMPILER_MSVC
+#ifdef _WIN32
// MSVC does not support the #warning directive.
int unused_variable__triggers_a_warning; // triggers C4101
#else // not COMPILER_MSVC
