-added missing file.

src/critsec.h

@@ -0,0 +1,37 @@
+#pragma once
+
+// System independent critical sections without polluting the namespace with the operating system headers.
+class FInternalCriticalSection;
+FInternalCriticalSection *CreateCriticalSection();
+void DeleteCriticalSection(FInternalCriticalSection *c);
+void EnterCriticalSection(FInternalCriticalSection *c);
+void LeaveCriticalSection(FInternalCriticalSection *c);
+
+// This is just a convenience wrapper around the function interface.
+class FCriticalSection
+{
+public:
+	FCriticalSection()
+	{
+		c = CreateCriticalSection();
+	}
+	
+	~FCriticalSection()
+	{
+		DeleteCriticalSection(c);
+	}
+
+	void Enter()
+	{
+		EnterCriticalSection(c);
+	}
+	
+	void Leave()
+	{
+		LeaveCriticalSection(c);
+	}
+
+private:
+	FInternalCriticalSection *c;
+
+};