error out if an exists condition tests an empty path, because that makes
authorespie <espie@openbsd.org>
Wed, 21 Jun 2017 00:11:36 +0000 (00:11 +0000)
committerespie <espie@openbsd.org>
Wed, 21 Jun 2017 00:11:36 +0000 (00:11 +0000)
commit663679869f8db359e6fa8611149e5cecfd86507f
tree057017c4b75ffe6492328f52afe57e41c85f69ae
parent82c015f87f1465b852e785283f6ee8557e0c510d
error out if an exists condition tests an empty path, because that makes
zero sense.

this would have caught DEPENDSFILE in gnu/cc/cc_tools

okay guenther@,  also tested by krw@
usr.bin/make/cond.c