libxslt1
    obsoletes "libxslt-<targettype>"
libxslt-devel
    requires -libxslt-<targettype>
    requires "libxslt1-<targettype> = <version>"
    obsoletes "libxslt-devel-<targettype> < <version>"
    provides "libxslt-devel-<targettype> = <version>"