Correct mpsc_dequeue

src/ptr_set.cpp

@@ -1,14 +1,3 @@
-template <typename T>
-struct TypeIsPointer {
-	enum {value = false};
-};
-
-template <typename T>
-struct TypeIsPointer<T *> {
-	enum {value = true};
-};
-
-
 template <typename T>
 struct PtrSet {
 	static_assert(TypeIsPointer<T>::value, "PtrSet::T must be a pointer");