ruby: re-enable macros.d/ruby for autodeps

previously disabled in cd352fdab2c780ade042a95bf0e4ec2e4c8fafba due
duplication

need to define only __ruby_provides and __ruby_requires, but as other
macros.d/* provide macros later overriden by macros.build, going to
accept this duplication here as well

(macros.build always overrides macros.d/* contents via due load order
specified by --with-path-macros configure option)