Mono: Enable threads suspend workaround on Windows

This appears to be necessary for current official builds cross-compiled
with MinGW from Linux, using Mono 6.6.0.160.

Follow-up to #31784, see #29812 for details.

modules/mono/mono_gd/gd_mono.cpp

@@ -356,7 +356,7 @@ void GDMono::initialize() {
 	}
 #endif
 
-#if !defined(WINDOWS_ENABLED) && !defined(NO_MONO_THREADS_SUSPEND_WORKAROUND)
+#if !defined(NO_MONO_THREADS_SUSPEND_WORKAROUND)
 	// FIXME: Temporary workaround. See: https://github.com/godotengine/godot/issues/29812
 	if (!OS::get_singleton()->has_environment("MONO_THREADS_SUSPEND")) {
 		OS::get_singleton()->set_environment("MONO_THREADS_SUSPEND", "preemptive");