GDB 9.1 release 2019-12-23 update

[Joel Brobecker <brobecker@adacore.com>]

Hi everyone,

So, as far as I know, the only issues that are still open are
the issues that Eli found with the pre-release.

  - [EliZ] readline/colors.c build failure

        Caused by S_IXGRP and S_IXOTH not being defined on MinGW.
        Patch sent to readline, and should be applied to our local
        tree soon.

  - [EliZ] configure warning when checking for pthread-config

        Problem understood, but EliZ blocked because he doesn't have
        the correct auto-tools version. Hopefully building those
        from source is an option.

  - [Eliz] libtcf fails to build on MinGW
        https://sourceware.org/bugzilla/show_bug.cgi?id=25155

        Problem reported to binutils on Dec 17th, but so far
        no answer as far as I can tell.
        https://sourceware.org/ml/binutils/2019-12/msg00277.html

        If we don't get an answer after the end of year holidays,
        I suggest we send in a patch, which will likely help move
        things along.  From Eli's message on bugzilla, we shouldn't
        be far from having one.

There might also be an issue with GDB/TUI, but that's less clear
at this stage.

Are there other issues that I may have missed for which we should
wait until we can release GDB 9.1?

Thank you!
-- 
Joel