System's errno.h inclusion cleanup follow-up.

System's errno.h is conditionally included from setup_once.h

Makefile.netware

@@ -354,6 +354,7 @@ else
 endif
 	@echo $(DL)#define HAVE_ARPA_INET_H 1$(DL) >> $@
 	@echo $(DL)#define HAVE_ASSERT_H 1$(DL) >> $@
+	@echo $(DL)#define HAVE_ERRNO_H 1$(DL) >> $@
 	@echo $(DL)#define HAVE_ERR_H 1$(DL) >> $@
 	@echo $(DL)#define HAVE_FCNTL_H 1$(DL) >> $@
 	@echo $(DL)#define HAVE_GETHOSTBYADDR 1$(DL) >> $@