Implement HlLoadSegment() intrinsics routine

sdk/xtdk/amd64/hlfuncs.h

@@ -63,6 +63,11 @@ XTCDECL
 VOID
 HlLoadGlobalDescriptorTable(IN PVOID Source);
 
+XTCDECL
+VOID
+HlLoadSegment(IN USHORT Segment,
+              IN PVOID Source);
+
 XTCDECL
 VOID
 HlLoadTaskRegister(USHORT Source);