Define more termios.h macros unconditionally for alpha (bug 21277)

[Joseph Myers]

On Mon, 27 Mar 2017, Adhemerval Zanella wrote:

> LGTM.  I guess the 'POSIX.1 ...' comment is out the place then?

The comment is not wrong, but it seems inappropriate in a single 
architecture-specific file when the point of the comment seems to be to 
relate to the removed #ifdef.

-- 
Joseph S. Myers
joseph@codesourcery.com