ObsoleteFiles.inc: Remove manpages from OLD_FILES

In 0a0f7486413c147d56808b38055c40c64cff61f5 sconfig.8.gz and apmd.8.gz
were moved back to the parent directory share/man/man8.

This conflicts with a previous entry in OLD_FILES so running 'make
delete-old' would delete the new installed files.

Reported by: marklmi@yahoo.com
Approved by: emaste@
Fixes: 0a0f7486413c - Build manpages for all architectures
MFH: 4 weeks
Differential Revision: https://reviews.freebsd.org/D31092