Fix termios constants on PPC architectures Some architectures, notably PPC and MIPS, use different ioctls for termios. This changes the constants to use the ones defined in golang.org/x/sys/unix which should handle edge case architectures better.
As of torvalds/linux@1b8b20868a6d64cfe8174a21b25b74367bdf0560, unsupported ioctls now return ENOTTY instead of EINVAL. This change was also backported to the 5.10 stable branch, so it's a problem on the current release of many Linux distros now.
