Add INIT_ALL_ZERO and INIT_ALL_PATTERN to kern.opts.mk

These options need to be in the kern.opts.mk file to be alive for kernel
and module builds. This also reverts r367579 since that's not needed with
this fix: the host's bsd.opts.mk is irrelevant.

Reviewed by: brooks@
Differential Revision: https://reviews.freebsd.org/D27170