Preparing for new release of FC host tools

[Mychaela Falconia]

Hello FreeCalypso community,

I am in the process of preparing a new release of FC host tools,
containing a bunch of recent changes, and in an effort to be nicer to
users of "modern" host systems (or more precisely, more "modern" than
my own taste) I have provisionally (experimentally) incorporated this
patch from Serg L from 2019-07-03:

https://www.freecalypso.org/pipermail/community/2019-July/000694.html

The root of problem appears to be that some miscreants have modified
recent Linux kernel versions (newer than linux-4.4.14 of Slackware
14.2) to insert a delay of 10 ms before select system call returns
when serial input is ready; this Linux kernel misbehaviour majorly
slows down many of our operations on affected "modern" host systems.
As figured out by the author of the user-contributed patch in
question, it appears that we need to set the ASYNC_LOW_LATENCY flag in
TIOCSSERIAL in order to get the old sane behaviour back, which is what
the patch does.

I have just incorporated this patch into the current not-yet-released
Hg version of FC host tools on a provisional/experimental basis:

https://www.freecalypso.org/hg/freecalypso-tools/

Before I can put out a formal release with this change included, I
need to be absolutely sure that it does not break anything for anyone,
hence I am asking our regular "bleeding edge" code users to test the
current version.  It would also be really nice if someone other than
Serg could test it on a "modern" Linux host system and confirm that it
really does improve performance of operations like fc-xram and flash
programming.

Hasta la Victoria, Siempre,
Mychaela aka The Mother