[PATCH] Add style tui-reverse command to colorize TUI current line.

[Eli Zaretskii]

> From: Andrei Pikas <gdb@mail.api.win>
> Date: Sat,  9 Jul 2022 22:05:45 +0300
> Cc: Andrei Pikas <gdb@mail.api.win>
> 
> Adds the ability to customize the colors of the current line of code in TUI.
> This may be desirable when code highlighting is enabled. Because higlighted
> keywords in dark blue color are indistinguishable from a black background
> (which is the default inverse color for a white terminal).
> Here is a screenshot of old and new behavior
> https://drive.google.com/file/d/1doYNdKRlEjsROUaP8DbanV4bBiam7EQl/view
> ---
>  gdb/NEWS            |  4 ++++
>  gdb/cli/cli-style.c | 34 ++++++++++++++++++++++++++++++++++
>  gdb/cli/cli-style.h |  3 +++
>  gdb/doc/gdb.texinfo |  3 +++
>  gdb/tui/tui-io.c    | 36 ++++++++++++++++++++++++++++++++----
>  gdb/tui/tui-win.c   |  1 +
>  6 files changed, 77 insertions(+), 4 deletions(-)

The documentation parts are okay, but I wonder why call this
"tu-reverse" when it is intended for the current line.  Why not
"tui-current-line" or somesuch?

Thanks.