possible to use old generated doc-* files as the source for new ones.
Wrong -mdoc files would then be installed, and man(1) failed with the
following diagnostics:
mdoc error: end-macro (.em) respecification is not allowed. (#41)
Should this have been `.Em ...'?
Put helper stuff into `beforedepend' to cleanup old files.
Makefile first infected in rev 1.15.
Reported via: -current