nonfatal dosym /usr/share/doc/${PF}/html/${PN} /usr/share/gtk-doc/html/${PN} dosym can only fail if ${D}/usr/share/gtk-doc/html does not exist. This is plain wrong. Also, please stop hacking gtk-doc install around, and let it install into the proper location rather than the custom, creepy, useless /usr/share/doc/${PF}/html.
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=50d57f188535544ba5dde67c1bddc9298b2dd765 Thanks for reporting.