lsfd: fill ENDPOINTS column for pty devices

lsfd: fill ENDPOINTS column for pty devices

An example output:

  $ ./lsfd -o+ENDPOINTS -Q '(COMMAND =~ "tmux") and ((SOURCE == "ptmx") or (SOURCE =~ "pts:.*"))'
  COMMAND          PID   USER ASSOC  XMODE TYPE SOURCE MNTID INODE NAME         ENDPOINTS
  tmux: client 3717086 yamato     0 rw----  CHR  pts:9    27    12 /dev/pts/9   2143274,xfce4-terminal,34rw
  tmux: client 3717086 yamato     1 rw----  CHR  pts:9    27    12 /dev/pts/9   2143274,xfce4-terminal,34rw
  tmux: client 3717086 yamato     2 rw----  CHR  pts:9    27    12 /dev/pts/9   2143274,xfce4-terminal,34rw
  tmux: server 3717088 yamato     5 rw---m  CHR  pts:9    27    12 /dev/pts/9   2143274,xfce4-terminal,34rw
  tmux: server 3717088 yamato     8 rw---m  CHR   ptmx    24   208 tty-index=16 3717089,zsh,0rw
                                                                                3717089,zsh,1rw
                                                                                3717089,zsh,2rw
                                                                                3717089,zsh,10rw

  $ ./lsfd -o+ENDPOINTS -Q '(PID == 3717089) and (FD == 0)'
  COMMAND     PID   USER ASSOC  XMODE TYPE SOURCE MNTID INODE NAME        ENDPOINTS
  zsh     3717089 yamato     0 rw----  CHR pts:16    27    19 /dev/pts/16 3717088,tmux: server,8rw

Signed-off-by: Masatake YAMATO <yamato@redhat.com>