lsfd: fill ENDPOINTS column of unix socket using UNIX_DIAG_PEER information
An example output:
# ./lsfd -Q '((PID == 1) || (PID == 1896)) && (TYPE == "UNIX-STREAM") && ((FD == 1) || (FD == 278))' -o+ENDPOINTS
COMMAND PID USER ASSOC XMODE TYPE SOURCE MNTID INODE NAME ENDPOINTS
systemd 1 root 278 rw---m UNIX-STREAM sockfs 9 37012 state=connected path=/run/systemd/journal/stdout 1896,ModemManager,1
ModemManager 1896 root 1 rw---- UNIX-STREAM sockfs 9 43126 state=connected 1,systemd,278
1870458,systemd-journal,68
Signed-off-by: Masatake YAMATO <yamato@redhat.com>