[Kernel/Memory] Implement DATETIME0

include/kernel/config_mem.hpp

@@ -6,6 +6,7 @@ namespace ConfigMem {
 	enum : u32 {
 		KernelVersionMinor = 0x1FF80002,
 		KernelVersionMajor = 0x1FF80003,
-		AppMemAlloc = 0x1FF80040
+		AppMemAlloc = 0x1FF80040,
+		Datetime0 = 0x1FF81020
 	};
 }

include/memory.hpp

@@ -118,6 +118,7 @@ public:
 
 	u32 getLinearHeapVaddr();
 	u8* getFCRAM() { return fcram; }
+	u64 timeSince3DSEpoch();
 
 	// Returns whether "addr" is aligned to a page (4096 byte) boundary
 	static constexpr bool isAligned(u32 addr) {