cmd/daemon: FD_CLOEXEC the listener socket and don't leak fd for the connection.
cmd/daemon: FD_CLOEXEC the listener socket and don't leak fd for the connection.

Otherwise the listener gets inherited by all the child processes (mostly
harmless) and subprograms run by bup-server inherit an extra fd for the
connection socket (problematic since we want the connection to close as soon
as bup-server closes).

Signed-off-by: Avery Pennarun <e03ccfb89d416c4697ad6970ce86a92c1c28a78e@gmail.com>

ToxicFrog/bup,tjanez/bup,apenwarr/bup,gevaerts/bup,apenwarr/bup,tjanez/bup,jbaber/bup,tjanez/bup,pombredanne/bup,pombredanne/bup,ToxicFrog/bup,gevaerts/bup,mhoeher/bup,pombredanne/bup,jbaber/bup,ToxicFrog/bup,ToxicFrog/bup,apenwarr/bup,jbaber/bup,pombredanne/bup,jbaber/bup,mhoeher/bup,tjanez/bup,apenwarr/bup,jbaber/bup,gevaerts/bup,gevaerts/bup,ToxicFrog/bup,pombredanne/bup,pombredanne/bup,tjanez/bup,mhoeher/bup,gevaerts/bup,tjanez/bup,mhoeher/bup,mhoeher/bup,jbaber/bup,mhoeher/bup