As you might have noticed in the past couple of days, make(1) started
issuing warnings for duplicate commands definitions on a target. I.e.

foo:
	echo 1
foo:
	echo 2

will now issue a warning that the commands for the second definition
will be ignored.

In order to fix these warnings without having to change a lot of Makefiles
in the tree, I've added a new .if directive where one can check if the
target in question has commands associated with it. So that we can do:

foo:
.if !commands(foo)
	echo 2
.endif

In order for your make build to succeed, please make sure that you rebuild
make(1) before you install the new rules in /usr/src/share/mk, so that
the commands(<target>) directive gets recognized.

christos