Fixed missing Requires: freetype2 for Fedora

This reverts https://github.com/OpenRA/OpenRA/pull/4305. While this works on clean VMs that build proper RPMs from source in the same environment where it will be installed later the `0%{?fedora}` or `0%{?suse}` RPM macros will always be zero on our Ubuntu build server which also feature a very old and hacked version of rpmbuild. I should have known that this will be a problem. Sorry.