cli: Split out platform-specific tty code for Windows/Linux
cli: Split out platform-specific tty code for Windows/Linux

Use common entry point names for the Linux and Win32 implementations;
add Win32 stubs.  Avoid including <termios.h> on Windows, as it breaks
the build.

Signed-off-by: Kevin Cernekee <3105dbb3dd63fbb4f6371cfb04adc6726f76c56b@gmail.com>

mtmiller/stoken,mtmiller/stoken,cernekee/stoken,cernekee/stoken,cernekee/stoken,cernekee/stoken,mtmiller/stoken,mtmiller/stoken