PostgreSQL install error

Issue Summary

There's a small typo in the installation SQL for Postgres databases. Specifically, in custom_pagers.install, this line:

      db_query("CREATE INDEX {custom_pagers}_pid_idx ON {custom_pagers} (pid)");

should be:

      db_query("CREATE INDEX {custom_pagers}_pid_idx ON {custom_pager} (pid)");

(The second "custom_pagers" should be "custom_pager" with no s).

Patch attached.

Thanks,
Curtis.