Double clicking action gets triggered by selecting different units

[Feldfeld]

It is possible to trigger the double clicking action by selecting 2 different units of the same type fast enough. Here is an example situation where it poses a problem:

If a player wants to select 2 women from a group of women in the same spot, then he would select one, hold shift and select another so that he has 2 in the selection. If he does that too fast, that will trigger double clicking and all women on the screen will be selected.

Note that I didn't have this problem in A23.

[wraitii]

I can reproduce this on A23 and A24 by clicking on the ground next to a unit, then moving the camera using the keyboard and clicking again, this time on a unit.

It seems SDL considers mouse motion only to reset double-clicks, and we use that directly. Fixing it would require storing the 'last clicked entity', which might actually be tricky to do correctly as we would need to reset it...

[wraitii]

In 24698:

Prevent double-click when moving the mouse.

SDL 2.0.9 introduced a 32-pixel leeway for double clicks to register, which makes it possible to trigger "select all units of the same type" behaviour while trying to select different units that are close by.

This effectively reverts that by setting the "hint" to 1.

Fixes #5920

Differential Revision: ​https://code.wildfiregames.com/D3420