In the future, this will be beneficial as we move the egid out of the
groups list; there's no need to track the egid explicitly in our
supplemental groups, and doing so could become a security issue if
setgid() would not end up switching groups[0] as it does today and
we end up wanting to change our egid.
The rwhod diff is a little gratuitious, but I like patterns and
setgroups() -> setgid() -> setuid() is a lot more common than
setgid() -> setgroups() -> setuid().
This is sweep is not exhaustive and intentionally did not include
contrib/, crypto/ or tools/.
Reviewed by: olce
Differential Revision: https://reviews.freebsd.org/D51510
Kyle Evans
1286fd8ecc