Fixed timer result register

git-svn-id: https://svn.inf.ethz.ch/svn/lecturers/a2/trunk@7746 8c9fc860-2736-0410-a75d-ab315db34111

source/Generic.Unix.AMD64.Machine.Mod

@@ -457,7 +457,10 @@ END SetRDI;
 
 PROCEDURE -GetTimer* (): HUGEINT;
 CODE {SYSTEM.Pentium}
+	XOR RAX, RAX
 	RDTSC	; set EDX:EAX
+	SHL RDX, 32
+	OR RAX, RDX
 END GetTimer;