building gdb with TUI support on Windows

[Eli Zaretskii]

> From: Joel Sherrill <joel.sherrill@oarcorp.com>
> Date: Thu, 1 Jan 2015 10:48:44 -0600
> CC: "ssbssa@yahoo.de" <ssbssa@yahoo.de>,"gdb@sourceware.org" <gdb@sourceware.org>
> 
> The other solution fixes it without any other user being impacted.

Only if the change will be submitted to the Readline maintainers.
Otherwise, each user will have to patch their sources, and do it for
each new version of GDB.