We don't need to build documentation for
gtk-doc using subprojects, not by default
at least, and our 'auto' option would
override the subproject 'disabled' default
in libnice's case.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-build/-/merge_requests/155>
option('nls', type : 'feature', value : 'auto', description : 'Enable native language support (translations)')
option('orc', type : 'feature', value : 'auto', description : 'Enable Optimized Inner Loop Runtime Compiler')
option('doc', type : 'feature', value : 'auto', description : 'Generate API documentation with hotdoc')
-option('gtk_doc', type : 'feature', value : 'auto', description : 'Generate API documentation with gtk-doc')
+option('gtk_doc', type : 'feature', value : 'disabled', description : 'Generate API documentation with gtk-doc')