Defines starting with `p' in bsd/kern

• PANICSTR bsd/kern/tty.c:2140
• PF_NOSTOP bsd/kern/tty_pty.c:177
• PF_PKT bsd/kern/tty_pty.c:174
• PF_REMOTE bsd/kern/tty_pty.c:176
• PF_STOPPED bsd/kern/tty_pty.c:175
• PF_UCNTL bsd/kern/tty_pty.c:178
• PIPSIZ bsd/kern/uipc_usrreq.c:335