Meson: Make sure to enable cairo support in pango
When building GTK with -Dauto_features=disabled the cairo feature in pango subproject gets disabled. However GTK requires pangocairo, so make sure it always gets enabled by default.
When building GTK with -Dauto_features=disabled the cairo feature in pango subproject gets disabled. However GTK requires pangocairo, so make sure it always gets enabled by default.