Add Memory utility to detect shutdown.

Core/MemMap.cpp

@@ -383,18 +383,15 @@ void DoState(PointerWrap &p)
 	p.DoMarker("ScratchPad");
 }
 
-void Shutdown()
-{
+void Shutdown() {
 	lock_guard guard(g_shutdownLock);
 	u32 flags = 0;
-
 	MemoryMap_Shutdown(flags);
-	base = NULL;
+	base = nullptr;
 	DEBUG_LOG(MEMMAP, "Memory system shut down.");
 }
 
-void Clear()
-{
+void Clear() {
 	if (m_pRAM)
 		memset(GetPointerUnchecked(PSP_GetKernelMemoryBase()), 0, g_MemorySize);
 	if (m_pScratchPad)
@@ -403,6 +400,10 @@ void Clear()
 		memset(m_pVRAM, 0, VRAM_SIZE);
 }
 
+bool IsActive() {
+	return base != nullptr;
+}
+
 // Wanting to avoid include pollution, MemMap.h is included a lot.
 MemoryInitedLock::MemoryInitedLock()
 {