Make the keystore domain enforcing.

Change-Id: I7ef479ac1806b0a52bb0145a82d6d4265edc1f3e
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Bug: 11518274

keystore.te

 type keystore, domain;
-permissive keystore;
 type keystore_exec, exec_type, file_type;
 
 # keystore daemon