> socket-flock.patch
>
>       use advisory locks to check if the unix socket can be deleted.
>       A running postmaster keeps a lock on that file. A starting
>       postmaster exits if the file exists and is locked, otherwise
>       it deletes the sockets and proceeds.
>       This avoid the need to remove manually the file after a postmaster
>       or system crash.
>       I don't know if flock is available on any system. If not we could
>       define a HAVE_FLOCK set by configure.