Handle MOVED_LIBS in `make *-old-files`

[emaste]

Summary

MOVED_LIBS is used when a library moves from one directory to another,
e.g. /usr/lib/libc++.so.1 to /lib/libc++.so.1.  Having two copies of
the same shared library (with the same so version) can cause trouble,
as shown in the referenced PR.

delete-old-files and delete-old-libs are two separate steps, so that
old libraries can be retained until third party software packages are
rebuilt or reinstalled.  Libraries listed in MOVED_LIBS are logically
equivalent to updating a library without changing the so version, and
should be removed as soon as possible, so handle them in *-old-files.

Leave them in *-old-libs for now, in case the user updates their tree
between running delete-old-files and delete-old-libs.

PR:             272642

[dim]

Yes, this is probably the better approach.

[dim]

Btw, this should be MFCd.