cairo-gobject: require rcairo
gdk3: require rcairo
gtk2: require rcairo
gtk3: require rcairo
gtksourceview3: require rcairo
gtksourceview2: require rcairo
poppler extconf.rb: require rcairo
poppler rbpoppler.h: require rcairo
poppler rbpoppler-image-mapping.c: require rcairo
poppler rbpoppler: require rcairo
poppler rbpoppler-page.c: require rcairo
rsvg2: require rcairo