Using the -a option with makewhatis(8) makes it scan every file under
the configured manpaths, instead of only the ones in directories that
match "man*". When localized man pages are present, this makes it so
files under the "$some_lang/man*" directories are also indexed, which
can lead, as shown in #28146, to `man w3m` displaying a localized man
page instead of the default english one from /usr/share/man/man1/w3m.1.
Without a mandoc.db in the manpath, man(1) behaves predictably, and
removing from -a from the makewhatis(8) invocations makes it behave
predictably even with a mandoc.db available.
Users who wish to use localized man pages are expected to configure
manpaths in man.conf(5) or use the MANPATH env var.
Fixes#28146
f732676052