alpha: make short build log available for division routines

This enables the Kbuild standard log style as follows:

AS arch/alpha/lib/__divlu.o
AS arch/alpha/lib/__divqu.o
AS arch/alpha/lib/__remlu.o
AS arch/alpha/lib/__remqu.o

Signed-off-by: Masahiro Yamada <[e-mail]>

arch/alpha/lib/Makefile

···
 AFLAGS___remlu.o =       -DREM -DINTSIZE
 
 $(addprefix $(obj)/,__divqu.o __remqu.o __divlu.o __remlu.o): \
-							$(src)/$(ev6-y)divide.S
-	$(cmd_as_o_S)
+						$(src)/$(ev6-y)divide.S FORCE
+	$(call if_changed_rule,as_o_S)