GDB: Remote target can now accept the form unix::/path/to/socket.

GDB: Remote target can now accept the form unix::/path/to/socket.

Allow target remote to use the unix::/path/to/socket syntax as well as just
plain /path/to/socket

gdb/

  * ser-uds.c (uds_open): Use parse_connection_spec to deal with the
    comm form unix::/path/to/socket.

  * serial.c (serial_open): Consider the "unix:" prefix when deciding which
    interface to use.