Bootstrap crunchgen for builds from older trees

[kevans]

Summary

A near-future change will switch the default WARNS to 6 globally, including for the rescue build. This change ensures that we bootstrap crunchgen on older trees so that the output is WARNS-clean.

To complete the change, wipe out the entire rescue objdir if we detect an older rescue.c skeleton -- the crunched_stub_t typedef was added in the WARNS fix, so it should be present in all corrected output from crunchgen.

[emaste]

tools/build/depend-cleanup.sh

53 ↗

(On Diff #77108)

perhaps we should drop the rXXXXXX references form these and put them in the same commit as the change that requires it - svn / git blame will find the right match and really the date is sufficient for the purpose of deciding it's been sufficiently long that we can delete it.

[emaste]

Fine with me, modulo revision comment

[kevans]

tools/build/depend-cleanup.sh

53 ↗

(On Diff #77108)

Sure, +1. I'll drop that from this one and merge this change with the next one.

I do have some concern because we often historically add these post-mortem, but to be honest we can just tack on the revision in the brief summary part if it really matters. I suspect it doesn't matter, though.