FEXCore: Support deferred signal mutex

This is part of FEXCore since it pulls in InternalThreadData, but is
related to the FHU signal mutex class.

Necessary to allow deferring signals in C++ code rather than right in
the JIT.

FEXHeaderUtils/FEXHeaderUtils/ScopedSignalMask.h

@@ -1,8 +1,8 @@
 #pragma once
 
 #include <FEXCore/Utils/CompilerDefs.h>
-#include <FEXCore/Utils/LogManager.h>
 
+#include <atomic>
 #include <cstdint>
 #include <mutex>
 #include <shared_mutex>