gmacros: Fix deprecations support with ICC
gmacros: Fix deprecations support with ICC

ICC defines __GNUC__ (to emulate GCC), but has its own method of
disabling deprecations.

https://bugzilla.gnome.org/show_bug.cgi?id=776562

johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib