MFC r209862:

MFC r209862:
For both i386 and amd64 pmap,
- change the type of pm_active to cpumask_t, which it is;
- in pmap_remove_pages(), compare with PCPU(curpmap), instead of
  dereferencing the long chain of pointers [1].
For amd64 pmap, remove the unneeded checks for validity of curpmap
in pmap_activate(), since curpmap should be always valid after
r209789.

git-svn-id: svn://svn.freebsd.org/base/stable/8@213901 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f