unix: add ioctl functions for termios on Linux

Add IoctlGetTermios and IoctlGetTermios to retreive and manipulate
Termios structures on Linux, akin to the already existing implementation
or Solaris.

If desired, functions conforming to POSIX tcgetattr/tcsetattr could be
implemented on top of these.

Change-Id: I2a71061bad2e632c597b6f6184ad6374c46a43ee
Reviewed-on: https://go-review.googlesource.com/47330
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
1 file changed