fix make variable overriding for package makefiles on the command line

SVN-Revision: 12204

include/subdir.mk

@@ -28,7 +28,7 @@ define subdir
     $(call warn,$(1),d,BD $(1)/$(bd))
     $(foreach target,$(SUBTARGETS),
       $(call warn_eval,$(1)/$(bd),t,T,$(1)/$(bd)/$(target): $(if $(QUILT),,$($(1)/$(bd)/$(target)) $(call $(1)//$(target),$(1)/$(bd))))
-		$(if $(findstring $(bd),$($(1)/builddirs-parallel)),$$(SUBMAKE),$$(_SINGLE)$$(SUBMAKE) -j1) \
+		$(if $(findstring $(bd),$($(1)/builddirs-parallel)),$$(SUBMAKE),$$(SUBMAKE) -j1) \
 			-C $(1)/$(bd) $(target) $(if $(findstring $(bd),$($(1)/builddirs-ignore-$(target))), || $(call MESSAGE,   ERROR: $(1)/$(bd) failed to build.))
         $$(if $(call debug,$(1)/$(bd),v),,.SILENT: $(1)/$(bd)/$(target))