Use MOVED_LIBS for libraries moved between /usr/lib and /lib.

[jhb]

Summary

Add a MOVED_LIBS variable similar to OLD_LIBS except that MOVED_LIBS
is used for the cases that a library's name doesn't change, but it
just moves between /usr/lib and /lib. This will be used by a future
change to auto-generate lib32 old files entries for which these cases
need to be ignored (a moved library remains in /usr/lib32).

Suggested by: emaste

[emaste]

LGTM with one comment you can consider. I didn't check for any missed entries that should become MOVED_LIBS.

ObsoleteFiles.inc

6–12

Perhaps we should add a brief explanation why, or a link to the handbook? Users leaving old libraries around for existing binaries is obvious to anyone who has dealt with this for some time but may not be apparent to someone new adding an entry.

I thought of this only because D33849 is an exception to this statement.

Perhaps something like "In this way users may avoid deleting old dynamic libraries still required by existing binaries." or so.

[jhb]

Note that I compared the before/after of list-old-files and list-old-libs before this change and after the lib32 change to find the places that needed to use MOVED_LIBS.

ObsoleteFiles.inc

6–12

Ok, but I should probably add this to the earlier commit rewriting the description here.

[jhb]

Rebase.