- fix (parallel) compilation error in ldso.c

  We have to generate sysnum.h to satisfy all includes of ldso.c

Makerules

@@ -199,7 +199,7 @@ $(interp): $(top_builddir)lib/interp.c
 	$(compile.c)
 	$(Q)$(STRIPTOOL) -x -R .note -R .comment $@
 
-$(ldso):
+$(ldso): | $(sub_headers)
 	@cd $(top_builddir); $(MAKE) lib/$(patsubst %.$(MAJOR_VERSION),%,$(notdir $@))
 
 $(libc):