Remove OSVERSION checks that do not make sense any more.

For example (${OSVERSION} >= 900000 && ${OSVERSION} < 900021) is always true,
as is (${OSVERSION} > 900002 || ${OSVERSION} < 900000 && ${OSVERSION} > 800107).

Regarding patches, when an EXTRA_PATCHES is no longer needed, I remove it, when
it is always needed, I renamed it, in one case, I merged two patches.

Differential Revision: https://reviews.freebsd.org/D2209