Revert "Get rid of MSVC's __int64"

This reverts commit d63f79325f.

Minecraft.Client/Timer.h

@@ -17,9 +17,9 @@ public:
     float passedTime;
 
 private:
-    int64_t lastMs;
-    int64_t lastMsSysTime;
-    int64_t accumMs;
+    __int64 lastMs;
+    __int64 lastMsSysTime;
+    __int64 accumMs;
 
 	double adjustTime;