BASE: SDL: Show SDL version in --version output

[lotharsm]

Inspired by @raziel-'s comment at #4788 (comment), this patch shows the currently running SDL2 version when using the --version command:

ScummVM 2.8.0git2438-g4b14cdd8fed (Mar  9 2023 08:31:57)
Using SDL backend with SDL 2.26.3
Features compiled in: Vorbis FLAC MP3 RGB zLib MPEG2 FluidSynth Theora VPX AAC A/52 FreeType2 FriBiDi JPEG PNG GIF taskbar TTS cloud (servers, local) ENet TinyGL OpenGL (with shaders)

Unfortunately, SDL_GetVersion is only available in SDL2+, so we can't exactly determine the version when using SDL1.

[ccawley2011]

I'd recommend adding a new function to OSystem to get the platform information string, both to keep platform-specific code self-contained, and because it would allow subclasses to append additional information like the OS version that would be useful to have in log files.

Unfortunately, SDL_GetVersion is only available in SDL2+, so we can't exactly determine the version when using SDL1.

SDL_Linked_Version() appears to be the SDL 1.2 equivalent to this function, so you might want to use that. It may also help to print the version of SDL that ScummVM was compiled with if it's different from the linked version.

[sev-]

While this is a good idea about expanding OSystem, still, at this moment, this change is functional, and our commandLine.cpp is riddled with ifdefs, so one more, one less, IMHO doesn't matter.

Though, SDL_Linked_Version() call for 1.2. would be good to add before the merge.

[sev-]

Thanks!