devel/p4 devel/p4api: cache distfiles in LOCAL

[asomers]

Summary

devel/p4 devel/p4api: cache distfiles in LOCAL

Perforce unhelpfully rebuilds their distfiles every few hours, changing the
archived files' timestamps in the process. This obviously changes their
checksums. Work around the issue by caching local copies of the distfiles and
using those for the checksums.

Also, set a sane DIST_SUBDIR since the distfiles are ambiguously named.

Also, take over maintainership from gordon.

[gordon]

Would it be better off to just not do checksumming for this and use the source as is?

[asomers]

In D14211#298084, @gordon wrote:

Would it be better off to just not do checksumming for this and use the source as is?

@mat requested that I use a local mirror rather than disable checksumming. And from a security perspective, that's certainly better. I also tried adding a post-patch step that would unzip the distfile, make the timestamps uniform, then rezip it. However, I ran into problems with that approach. Chiefly, I couldn't figure out how to stop that step from running when it shouldn't. For example, it would run during the extract phase, which breaks poudriere because /portdistfiles is mounted read-only during that phase.

[mat]

In D14211#298084, @gordon wrote:

Would it be better off to just not do checksumming for this and use the source as is?

No.

[gordon]

Okay, based on that, looks good to me.