Git: Use consistent ordering for Merge Tool dialog

On Windows it is "Ignore, Merge Tool, Skip, Abort", while on Linux it is
"Merge Tool, Ignore, Skip, Abort"

That makes Ignore default on Windows, which is confusing

Change-Id: Id7e9e8dd6fd5748d518de4d94db47ae075268627
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>