[Lazarus] Mouse horiz scroll support

[Mattias Gaertner]

On Wed, 29 Nov 2017 16:53:15 +0300
Alexey via Lazarus <lazarus at lists.lazarus-ide.org> wrote:

> LCL don't support it.
> Pls apply this diff- only constant LM_MouseHWHeel
> 
> https://msdn.microsoft.com/en-us/library/windows/desktop/ms645614(v=vs.85).aspx

I added it.

Mattias