gplugin/gplugin

Make doc/introspection options yield to parent.
develop
2020-08-22, Elliott Sales de Andrade
71e98ba93d21
Make doc/introspection options yield to parent.

This allows `meson -Ddoc=false` to automatically propagate from Pidgin to the gplugin subproject, without having to specify `-Dgplugin:doc=false`.

Reviewed at https://reviews.imfreedom.org/r/87/
The following individuals have contributed to this project.
Ankit Vani <a@nevitus.org>
EionRobb <eion@robbmob.com>
Elliott Sales de Andrade <quantum.analyst@gmail.com>
Gary Kramlich <grim@reaperworld.com>
Jason Scherer <schereja@gmail.com>
John Bailey <rekkanoryo@rekkanoryo.org>
Mike Ruprecht <cmaiku@gmail.com>
Olaf Hering <olaf@aepfle.de>
Richard Laager <rlaager@pidgin.im>