bug#36832: Supply option to suppress scrolling in compilation mode buffers.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 30 Jul 2019 19:32:35 +0000
> Cc: 36832@debbugs.gnu.org
> From: Alan Mackenzie <acm@muc.de>
> 
> The current code does two things, sometimes, on <CR> being hit: (i) it
> puts an indicator into the fringe; (ii) it scrolls the compile mode
> window upwards, the pertinent line moving either to the top, or to a
> specified window line.
> 
> Unfortunately, the code which does these things seems to be fragmented,
> and there is just one user option to control (i) and (ii) above.
> 
> One solution would be always to mark to the line in the compile mode
> window, whether by an indicator in the fringe or a ">" or "=>" at column
> 0.  Then only scroll the compile mode window when the user has explicitly
> requested this by the user option compilation-context-lines.

Yes, that would be an okay solution.

> Why do these little things so often turn out to be so complicated?  ;-(

;-)