unix: use runtime.KeepAlive in Solaris IoctlSetTermio
unix: use runtime.KeepAlive in Solaris IoctlSetTermio

This ensures that value remains live for the duration of the ioctl system call.
This pattern is used in all other IoctlSet* functions but appears to have been
forgotten here.

Change-Id: I2b26a5c4e7c862f779427b839327b36c1bc78c82
Reviewed-on: https://go-review.googlesource.com/c/sys/+/259637
Trust: Matt Layher <76528ff2e917253aa2211f68e4ca60b5b846dcf5@gmail.com>
Run-TryBot: Matt Layher <76528ff2e917253aa2211f68e4ca60b5b846dcf5@gmail.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

golang/sys,golang/sys,golang/sys