Make the implementations of the work-stealing queue(s) selectable

emper/lib/adt/LockedQueue.hpp

@@ -7,9 +7,13 @@
 #include <type_traits>
 
 #include "Common.hpp"
-#include "Fibril.hpp"
 #include "StealingResult.hpp"
 
+// Forward declaration, declared and defined in Fibril.hpp.
+namespace emper {
+void maybeLockFibril(void* queueItem);
+}
+
 namespace adt {
 
 template <typename I, const uintptr_t SIZE>
@@ -62,11 +66,7 @@ class LockedQueue {
 		// by Schmaus et al. [schmaus2021nowa], Figure 6. and Listing 2.
 		if constexpr (emper::CONTINUATION_STEALING_MODE_LOCKED &&
 									std::is_same<AbstractFiber*, I>::value) {
-			AbstractFiber* abstractFiber = static_cast<AbstractFiber*>(*itemPtr);
-			Fibril* fibril = abstractFiber->asFibrilIfPossible();
-			if (fibril) {
-				fibril->fibrilMutex.lock();
-			}
+			emper::maybeLockFibril(*itemPtr);
 		}
 
 		deque.pop_front();