Update scriptlets and requirements
Since Fedora 28, ldconfig is automatically run as a file trigger, so
it is no longer necessary to call it from package scriptlets
(cf. https://fedoraproject.org/wiki/Changes/Removing_ldconfig_scriptlets).
Also, in commit 89aa83ab308550f4b7bfb4949fbad6362b6a91a5, "PreReq:
freetype" was replaced with "Requires(pre): freetype". While this is
effectively the same, the latter suggests that a "%pre" scriptlet
exists that needs freetype to run. As fontconfig does not have a
"%pre" scriptlet, this change replaces it again with a "PreReq" tag.