run-tests.sh: add regression test for bug with multiple named entities.

run-tests.sh: add regression test for bug with multiple named entities.

Michał Bartoszkiewicz just reported a very bad bug in the latest
release. When multiple named-user and named-group entries exist, the
later entries clobber earlier ones in the list. So if there are two
default ACL entries on a parent directory for group:bar and group:foo,
then apply-default-acl will create two entries on a child but both
wind up with the permissions of the group:foo entry. The full test
case he provided is as follows:

  $ getfacl -n .
  # file: .
  # owner: 1000
  # group: 1000
  user::rwx
  group::r-x
  other::r-x
  default:user::rwx
  default:group::r-x
  default:group:1:---
  default:group:2:rw-
  default:mask::rwx
  default:other::r-x

  $ touch foo
  $ getfacl -n foo
  # file: foo
  # owner: 1000
  # group: 1000
  user::rw-
  group::r-x            #effective:r--
  group:1:---
  group:2:rw-
  mask::rw-
  other::r--

  $ apply-default-acl foo
  $ getfacl -n foo
  # file: foo
  # owner: 1000
  # group: 1000
  user::rw-
  group::r--
  group:1:rw-
  group:2:rw-
  mask::rw-
  other::r--

This commit adds a new regression test that creates multiple default
named-user and named-group entries at once (with different
permissions!) and checks that they get applied correctly.