check/delete-old: Auto-generate lib32 entries for libraries.

check/delete-old: Auto-generate lib32 entries for libraries.

- Add usr/lib32/libfoo.so.N for lib/libfoo.so.N.

- Add usr/lib32/foo for usr/lib/foo.

- Treat casper libraries special since they are installed to
  /usr/lib32 instead of /usr/lib32/casper and thus map
  usr/lib/casper/foo to usr/lib32/foo.

Note that OLD_DIRS and MOVED_LIBS entries are not duplicated, only
OLD_FILES and OLD_LIBS.

Reviewed by:	imp, emaste
Sponsored by:	The University of Cambridge, Google Inc.
Differential Revision:	https://reviews.freebsd.org/D33324

(cherry picked from commit 77da558ceb0949b60b566da61cb8d9b9634ca862)