Clear the symbol map between each test.

This way we could, for example, test function replacement properly.

Actually slows down tests because it spends more time correctly
determining the function boundaries.

Core/Debugger/SymbolMap.cpp

@@ -615,15 +615,21 @@ void SymbolMap::AssignFunctionIndices() {
 void SymbolMap::UpdateActiveSymbols() {
 	// return;   (slow in debug mode)
 	lock_guard guard(lock_);
-	std::map<int, u32> activeModuleIndexes;
-	for (auto it = activeModuleEnds.begin(), end = activeModuleEnds.end(); it != end; ++it) {
-		activeModuleIndexes[it->second.index] = it->second.start;
-	}
 
 	activeFunctions.clear();
 	activeLabels.clear();
 	activeData.clear();
 
+	// On startup and shutdown, we can skip the rest.  Tiny optimization.
+	if (activeModuleEnds.empty() || (functions.empty() && labels.empty() && data.empty())) {
+		return;
+	}
+
+	std::map<int, u32> activeModuleIndexes;
+	for (auto it = activeModuleEnds.begin(), end = activeModuleEnds.end(); it != end; ++it) {
+		activeModuleIndexes[it->second.index] = it->second.start;
+	}
+
 	for (auto it = functions.begin(), end = functions.end(); it != end; ++it) {
 		const auto mod = activeModuleIndexes.find(it->second.module);
 		if (it->second.module == 0) {