[Ada] Fix serial port baud rate setting on GNU/Linux

[Iain Sandoe]

Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> wrote:
>
>> Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> wrote:
>>
>>> Hi Pierre-Marie,
>>>
>>>> This fixes an issue when setting the baud rate. The baud rate is set
>>>> using the cfsetospeed and cfsetispeed system calls. The code is using
>>>> speed_t for clarity. The non-blocking status is only reset when Block is
>>>> True. And serial blocking mode is now properly set according to termios
>>>> manual.
>>>>
>>>> Add documentation about a way to debug and test a serial port on
>>>> GNU/Linux without the need for a physical serial port.
>>>>
>>>> Tested on x86_64-pc-linux-gnu, committed on trunk
>>>
>>> this patch broke Linux/x86_64 bootstrap (Fedora 29):
>>
>> also Darwin (which seems to be using g-sercom-linux.adb)
>
> ah.  In hindsight, I'd wondered why my Solaris builds weren't affected.
> termios is common to all POSIX targets after all.

Actually, the linux file seems to contain quite a bit more advanced than  
SUSv3,
it might be worth having a Posix_susv3 version (there are quite a few targets
qualified to SUSv3, but it seems not many [1?] qualified to UNIX7).

Iain