Implement HlLoadGlobalDescriptorTable() intrinsic

sdk/xtdk/amd64/hlfuncs.h

@@ -59,6 +59,10 @@ VOID
 HlIoPortOutLong(IN USHORT Port,
                 IN ULONG Value);
 
+XTCDECL
+VOID
+HlLoadGlobalDescriptorTable(IN PVOID Source);
+
 XTCDECL
 VOID
 HlLoadTaskRegister(USHORT Source);