I had to make changes to SDL.dll
Regardless of portability, this looks IMHO like a too expensive thing to do. It means the dev team has to maintain an own project-specific version of SDL. Once you want to upgrade to SDL2 or similar you have big problem.
Linux-side modification to SDL is not possible in this manner, unless you include SDL in the oolite git repository and set up the build process to use it, see above. The dependency for compilation (libsdl1.2-dev) is downloaded from the distribution's repositories when setting up the build environment (on Ubuntu). I suppose the windows build package includes the SDL code ?!
My code above is hack-ish. A better solution should probably pre-modify the delta_t passed to that function. I guess that's what you tried.
A similar problem exists for how mouse movement translates into roll/pitch/yaw btw., which is also not configurable, and which I solved by modifying the
This could be a similar configurable option.
warning sound if a missile is inbound: Missile warning