Log Message:
some clean up:

Makefile
* xmlto is just required to docbook_docs, move dependency to `doc' option.
* remove buildlinking to gobject-introspection, it is alrady in option.mk
  conditionally.
* gdk_pixbuf2 is really requied by this package, drop specification of `build'
  dependency.
* exactly specify required glib2 version.
* from NEWS, libnotify>=7.0 use GBus instead of dbus-glib, so drop dependency
  on dbus and dbus-glib.
* change dependency on gtk3 to `build',  it is just required to test build.

buildlink3.mk
* change ABI_DEPENDS to reasonable version.
* drop `doc' and `introspection' option condition handling , it will not affect
  to packages usind this file or should be handled packages by themselves.
* drop buildlinking to dbus and dbus-glib and add to gdk-pixbuf2, same reason
  as Makefile.

options.mk
* gtk-doc documents are already in release taball, so dtk-doc is not required
  to build, reuse as docbook-docs to match PLIST.doc condition.
* exactly specify required gobject introspection version.

Bump PKGREVISION.