rust wip PKGNAMEs, DIST_SUBDIR

[Greg Troxel <gdt%lexort.com@localhost>]

I just tried to "make replace" in wip/rust173, and that failed because
it sets PKGNAME to

  rust173-bin-1.73.0.tgz

rather than what I expected as

  rust-bin-1.73.0.tgz

To me, the idea is that you can just build from these instead of
lang/rust if you want to test the upcoming rust.  This PKGNAME prevents
the replace, and I would expect it to cause the bl3 machinery to not
recognize it as a valid rust packge and to install lang/rust-bin.

I have therefore adjusted PKGNAME to be just rust-bin, and that enabled
make replace to work.



Separately, I see that this packages sets DIST_SUBDIR, and we usually
use that when upstream has (wrongly, always) modified distfiles after
publication.  But these are just files with versions that are being put
in directories with that version, so DIST_SUBDIR is not remediating
replaced distfiles, and is just creating a lot of directories.  We have
not, so far, other than mitigating replaced distfiles -- or distfiles
with no version (tex), generally placed things in subdirs, except to
avoid name collisions arising form distfiles that aren't named properly
(e.g. schilytools, openblas).

Is there any reason to keep DIST_SUBDIR?