Implement patty_strlcpy() for portability and correctness, to provide
BSD strlcpy() functionality for glibc systems while ensuring a nul
terminated string is written to a destination, truncating the source
string by one byte if need be to make room for the nul terminator
Changes:
* Modify patty_client_new() to accept NULL as a Unix domain socket
path; when NULL is provided, search for the pattyd(8) socket in
pattyd.sock, followed by the default full socket path,
/var/run/patty/patty.sock
* Modify bin/ax25dump.c, bin/tncd.c to use default socket paths when
calling patty_client_new() by defaulting to NULL when no -s flag
is provided
Changes:
* Ensure TNC PTYs are closed on error
* Instead of waiting indefinitely, use patty_client_ping() to poll
the status of the patty daemon to exit in a timely manner
