Obsoletefiles.inc: A few OpenSSL 3 cleanups.

• Treat old engine DSOs from OpenSSL 1.1.1 as OLD_LIBS, not OLD_FILES. These should only be deleted by make delete-old-libs similar to how PAM modules are treated.

• Add /usr/lib32/engines to OLD_DIRS. lib32 automation does not apply to OLD_DIRS.

Reviewed by: Pierre Pronchery <pierre@freebsdfoundation.org>
Differential Revision: https://reviews.freebsd.org/D41034