Add neverallow checking to sepolicy-analyze.

See NEVERALLOW CHECKING in tools/README for documentation.

Depends on change I45b3502ff96b1d093574e1fecff93a582f8d00bd
for libsepol to support reporting all neverallow failures.

Cherry-pick of commit: 59906bf8
with build-fix from commit: 74bbf703
added manually.

Bug: 19191637

Change-Id: I1c18fa854b3c5f5e05d5dc42d9006c5fdacebdc3
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>