x:=x*1 created wrong code for m68k

tests/tbs/tb0431.pp

@@ -0,0 +1,12 @@
+{ the smallest falling test I ever found PM }
+{ the code generated a shll #0,%edx on i386
+  which was bad but harmless...
+  but on m68K it generated a asl.l #0,%d2
+  which is not correct ... }
+
+var
+  x : longint;
+begin
+  x:=5;
+  x:=x*1;
+end.