Store the current name of the ACL with each history row, and index
the name.  This will eventually allow retrieval of history by name
for ACLs that have been deleted, although the rest of the code is
not yet in place.

The initial creation and membership of the ADMIN ACL during database
initialization or reinitialization is no longer recorded in the
acl_history table, since otherwise it produces errors due to the
missing ah_name field when building the database with schema 0.07.
There should be some better solution to this, but this will be okay
for the time being.

Change-Id: I015a00c972e0c2730c3d449952fcfe9b79c6e54f
Reviewed-on: https://gerrit.stanford.edu/1553


Reviewed-by: Russ Allbery <rra@stanford.edu>
Tested-by: Russ Allbery <rra@stanford.edu>