Simutrans 124.0 implicitly made Freetype a required dependency, but this change was not reflected on the build system. As a consequence, some users (@Flemmbrav) have been building without Freetype, only to find that the game does not start as it can't load any fonts.
This patch removes the USE_FREETYPE compile flag and related options. When necessary, the compile flag has been replaced by COLOUR_DEPTH != 0, so that server builds can be compiled without freetype.
The behavior now for CMake is that if Freetype is not found then it fallback to a server build (sames as if SDL2 is not found). You can discuss if this is the desired behavior or if we should make Freetype/SDL2 mandatory if no backend has been defined.
For other build systems, I have not looked much into the autoconfiguration. You may want to complete this patch with whatever is necessary.
The server builds should not use freetype. But indeed, otherwise it has become mandatory. I am fine with that.
EDIT: I added it to autoconf and submitted it.
EDIT2: breaks the Android built (which is cmake)
Edit3: SDL include cannot be found on Android?!?
It was because Freetype was not being search for in the Android build, therefore Freetype_FOUND was not set.
I have moved those checks to SimutransBackend.cmake (indeed, they make more sense there), and the Android build works again.
Thank you, success confirmed