bsdinstall/zfsboot: Remove unused global variable

[concussious.bugzilla_runbox.com]

Summary

In an AMA session on the FreeBSD Discord, it was revealed that no
logic remains calling GPART_BOOTCODE_PARTONLY. It was removed in
aa2a0e0fc311 for FreeBSD 12. git grep shows no other references.
No functional change intended.

MFC after:      2 weeks
Fixes:          aa2a0e0fc311 (Enable new UEFI+GELI support)
Reported by:    Antranig Vartanian <[e-mail]>
Reviewed by:    mhorne
Approved by:    mhorne (src)
Approved by:    mhorne, carlavilla (mentors)

[mhorne]

Agreed with the change. The message and "Fixes" line should actually point to aa2a0e0fc3114ecb275fba6564d92e94a7039fa9.

[concussious.bugzilla_runbox.com]

Thank you. How does it work since this is not doc? Since you have a src bit and have approved it, do I commit this? Also, in general, if you have approved it, do I still wait for Sergio? If not, do I put him as implicit or do I omit from the commit message?

[mhorne]

In D48086#1096806, @concussious.bugzilla_runbox.com wrote:

Thank you. How does it work since this is not doc? Since you have a src bit and have approved it, do I commit this? Also, in general, if you have approved it, do I still wait for Sergio? If not, do I put him as implicit or do I omit from the commit message?

I will wait to see the updated commit message before I give my approval, but when I do it can be indicated like this:

Reviewed by: mhorne
Approved by: mhorne (src)
Approved by: mhorne, carlavilla (mentors)

As a doc committer making a change outside of your area, you are required to get review and approval from a src committer. This is independent from the mentor approval required during your mentorship period. Note that this is a socially-enforced requirement, but on a technical level your commit bit has the privileges to push to any repository, so please use this power responsibly. For me, when I make changes to the ports tree (even to the port I maintain), I get review and approval from a ports committer.

@carlavilla might give his approval for this change, but in general you are not required to wait for both of us; the approval of one mentor is enough to say that this commit has been checked and is ready to proceed.

See also: https://docs.freebsd.org/en/articles/committers-guide/#_policy_for_committer_activity_in_other_trees

[concussious.bugzilla_runbox.com]

Update commit message per instructions.

so please use this power responsibly.

:salute: