Bug 1368920. Part 1 - AC_SUBST MOZ_DEV_EDITION so it can be used in moz.build. r=ted

MozReview-Commit-ID: AghBiQ7CG4w

--HG--
extra : rebase_source : cdd4a682d120c1eef669860f36fa01f12001cf7a

old-configure.in

@@ -5397,6 +5397,7 @@ if test "$ACCESSIBILITY" -a "$MOZ_ENABLE_GTK" ; then
     AC_DEFINE_UNQUOTED(ATK_REV_VERSION, $ATK_REV_VERSION)
 fi
 
+AC_SUBST(MOZ_DEV_EDITION)
 if test -n "$MOZ_DEV_EDITION"; then
     AC_DEFINE(MOZ_DEV_EDITION)
 fi