retire BSD_CRTBEGIN option

[emaste]

Summary

BSD_CRTBEGIN is enabled on all archs (except sparc64) and non-BSD csu will be removed along with gcc 4.2.1.

This change will not be committed until one of the following is true:

• someone adds sparc64 support to BSD_CRTBEGIN
• we reach the gcc 4.2.1 removal date and leave sparc64 broken
• there is a decision to proceed with this earlier than gcc 4.2.1 removal, leaving sparc64 broken but with the hope that it gets fixed

[emaste]

@sjg I did not change all of the .depend files, I assume they can be regenerated and committed after this change gets in

[sjg]

There should not be any active depends mentioning gnu/lib/csu - that's the point of the filters,
any stale entries will be ignored - if the directory is gone.

contrib/bmake/mk/meta2deps.sh

52 ↗

(On Diff #66591)

I would skip this one - its just an example

share/mk/meta2deps.sh

52 ↗

(On Diff #66591)

again just an example

[emaste]

contrib/bmake/mk/meta2deps.sh

52 ↗

(On Diff #66591)

Sure it's just an example but once gnu/lib/csu is gone it might be confusing rather than informative

[brooks]

LGTM

[emaste]

there is a decision to proceed with this earlier than gcc 4.2.1 removal, leaving sparc64 broken but with the hope that it gets fixed

@imp proposed a new timeline on the -arch mailing list which has sparc64 removal moved to 2020-01-31. Regardless of whether that happens or not I think it's a fair date for this change.