Fix an issue with service(8) where utilities such as screen(1) and tmux(1)
would behave differently when utilizing rc-script was invoked manually vs.
service(8). The issue being that these utilities require the TERM environ
variable to be set and service(8) was not passing it down.

Reported by:	Michael Dexter <editor@callfortesting.org>
PR:		bin/191869
Reviewed by:	allanjude
MFC after:	3 days
X-MFC-to:	stable/10, stable/9