add missing FreeType dependency to RPM

http://pkgs.org/download/freetype
add SDL2 as soft dependency to RPM

http://pkgs.org/download/SDL2
add SDL2 as soft dependency to DEB

http://pkgs.org/download/libsdl2-2.0-0
add regular SDL2 dependency on rolling release Arch PKG

https://www.archlinux.org/packages/extra/i686/sdl2/