[tz] [PROPOSED] Port ar usage to POSIX

[Paul Eggert]

* Makefile (libtz.a): Use 'ar -rc' instead of 'ar ru', as
'ar -rc' is standardized by POSIX and GNU 'ar' 2.26.1 (Ubuntu
16.04.1) warns about the obsolete form 'ar ru'.
---
 Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 74b950c..1b714a8 100644
--- a/Makefile
+++ b/Makefile
@@ -542,7 +542,8 @@ force_tzs:	$(TZS_NEW)
 		cp $(TZS_NEW) $(TZS)
 
 libtz.a:	$(LIBOBJS)
-		$(AR) ru $@ $(LIBOBJS)
+		rm -f $@
+		$(AR) -rc $@ $(LIBOBJS)
 		$(RANLIB) $@
 
 date:		$(DATEOBJS)
-- 
2.7.4