selinux: validate permissive and neveraudit map types at load

The permissive and neveraudit maps are read as ebitmaps and indexed by
type value, but their set bits are never checked. A bit that is not a
defined, non-attribute type is silently accepted. Validate every set bit
of both maps in policydb_index() with policydb_simpletype_isvalid().

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>