Cleanup trailing newlines noticed while looking for other issues.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@274528 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Automate options INET/INET6 turning into MK_$opt_SUPPORT
correctly. Fixes if_gfe when building without INET6 and
simplifies if_gif's Makefile.

Sponsored by: Netflix, Inc


git-svn-id: svn+ssh://svn.freebsd.org/base/head@274529 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f