gnextstepsettingsbackend: Use same token for function-call and its availability
gnextstepsettingsbackend: Use same token for function-call and its availability

Availability of the g_nextstep_settings_backend_get_type() prototype
is controlled by HAVE_COCOA in gsettingsbackendinternal.h and the
actual implemenation by OS_COCOA in Makefile.am. Therefore, the
giomodule.c call to that function should also be protected by a COCOA
token rather than an CARBON token (cocoa and carbon are independent
autoconf tests).

https://bugzilla.gnome.org/show_bug.cgi?id=731425

cention-sany/glib,mzabaluev/glib,gale320/glib,gale320/glib,endlessm/glib,Distrotech/glib,tchakabam/glib,tchakabam/glib,lukasz-skalski/glib,lukasz-skalski/glib,krichter722/glib,cention-sany/glib,ieei/glib,endlessm/glib,cention-sany/glib,mzabaluev/glib,tchakabam/glib,ieei/glib,tamaskenez/glib,Distrotech/glib,krichter722/glib,gale320/glib,ieei/glib,mzabaluev/glib,johne53/MB3Glib,krichter722/glib,johne53/MB3Glib,gale320/glib,cention-sany/glib,krichter722/glib,johne53/MB3Glib,cention-sany/glib,endlessm/glib,mzabaluev/glib,Distrotech/glib,MathieuDuponchelle/glib,tamaskenez/glib,endlessm/glib,endlessm/glib,tamaskenez/glib,tchakabam/glib,MathieuDuponchelle/glib,ieei/glib,tamaskenez/glib,MathieuDuponchelle/glib,gale320/glib,tchakabam/glib,johne53/MB3Glib,tamaskenez/glib,lukasz-skalski/glib,johne53/MB3Glib,johne53/MB3Glib,lukasz-skalski/glib,lukasz-skalski/glib,MathieuDuponchelle/glib,Distrotech/glib,ieei/glib,MathieuDuponchelle/glib,mzabaluev/glib,krichter722/glib,Distrotech/glib