configure.ac: remove unused macros
configure.ac: remove unused macros

And follow the recommendations from
http://live.gnome.org/GnomeGoals/ModernAutotools

Signed-off-by: Víctor Manuel Jáquez Leal <853e0dbb5ddd43a0f0483f24794ae05c4c52af91@igalia.com>

GNOME/grilo-plugins,vrutkovs/grilo-plugins,MathieuDuponchelle/grilo-plugins,kyoushuu/grilo-plugins,MathieuDuponchelle/grilo-plugins,MathieuDuponchelle/grilo-plugins,jasuarez/grilo-plugins,kyoushuu/grilo-plugins,vrutkovs/grilo-plugins,vrutkovs/grilo-plugins,MikePetullo/grilo-plugins,MikePetullo/grilo-plugins,MikePetullo/grilo-plugins,jasuarez/grilo-plugins,GNOME/grilo-plugins,MathieuDuponchelle/grilo-plugins,grilofw/grilo-plugins,grilofw/grilo-plugins,vrutkovs/grilo-plugins,kyoushuu/grilo-plugins