BUG #2088: logfiles only readable by instance owner

The following bug has been logged online:

Bug reference:      2088
Logged by:          Dick Snippe
Email address:      Dick.Snippe@tech.omroep.nl
PostgreSQL version: 8.1.0
Operating system:   Fedora Core 2
Description:        logfiles only readable by instance owner
Details:

when redirect_stderr = true
the logfiles created by log_filename are only readable by the postgres
instance owner.
I assume this is caused by umask((mode_t) 0077) on line 414 in
scr/backend/postmaster/postmaster.c

setting umask 077 makes sense for the data files, but not per se for the
logfile.
It would be nice if the logfile mode was configurable, or defaulted to 644
or 640.
A similar scheme to setting the permissions on unix_socket_directory could
perhaps be used.