Implement HlReadGSQuadWord() intrinsic

sdk/xtdk/amd64/hlfuncs.h

@@ -67,6 +67,10 @@ XTCDECL
 ULONG_PTR
 HlReadControlRegister(IN USHORT ControlRegister);
 
+XTCDECL
+ULONGLONG
+HlReadGSQuadWord(ULONG Offset);
+
 XTCDECL
 ULONGLONG
 HlReadModelSpecificRegister(IN ULONG Register);