Makefile.inc1: unbreak bootstrap when kbdcontrol does not exist

Approved by: re (cperciva)
Submitted by: Evgeniy Khramtsov
Reviewed by: arichardson
Sponsored by: Rubicon Communications, LLC ("Netgate")

(cherry picked from commit 50179c5ec7d09d7b02497caf95dca5d33f93bcd9)
(cherry picked from commit 1048c56784c0e1d044b6828b030f326e48eaba28)