Remove mklocale(1) and colldef(1) which are deprecated since FreeBSD 11

In FreeBSD 11 along with the rework on the collation, mklocale(1) and colldef(1)
has been replaced by localedef(1) (a note has been added to the manpage to state
it).
mklocale(1) and colldef(1) has been kept around to be able to build older
versions of FreeBSD. None of the version requiring those tools are supported
anymore so it is time to remove them from base