MFC rev. 227629, stable/9 rev 228041:

MFC rev. 227629, stable/9 rev 228041:
Wire the kernel text RWX, rather than RX. We're not quite ready
for having kernel text non-writable, because we still need to
apply relocations. On top of that, the PBVM page table has all
pages marked as RWX, so it's an inconsistency to begin with.

Approved by:	re (kib)

git-svn-id: svn://svn.freebsd.org/base/releng/9.0@228042 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f