o A new patch that contains the following changes:
-- The pg_pwd file is now cached in the postmaster's memory.
-- pg_pwd is reloaded when the postmaster detects a flag file creat()'ed
by a backend.
-- qsort() is used to sort loaded password entries, and bsearch() is
is used to find entries in the pg_pwd cache.
-- backends now copy the pg_user relation to pg_pwd.pid, and then
rename the temp file to be pg_pwd.
-- The delimiter for pg_pwd has been changed to a tab character.
