Raw serial I/O requires clearing IEXTEN
Raw serial I/O requires clearing IEXTEN

It's default-on in OpenBSD.  Turning it off makes it stop dropping
the input bytes that were making the read-back for verify fail.

mattairtech/BOSSA,shumatech/BOSSA,mattairtech/BOSSA,shumatech/BOSSA,shumatech/BOSSA,etherkit/BOSSA,etherkit/BOSSA,femtoio/BOSSA,femtoio/BOSSA,femtoio/BOSSA,etherkit/BOSSA,mattairtech/BOSSA