$NetBSD: patch-Makefile,v 1.3 2017/10/18 20:25:41 adam Exp $

Do "install -c".

--- Makefile.orig	2017-10-15 15:59:36.000000000 +0000
+++ Makefile
@@ -126,7 +126,7 @@ install-libs: install-libs-yes
 
 install-data: $(DATA_FILES)
 	$(Q)mkdir -p "$(DATADIR)"
-	$(INSTALL) -m 644 $(DATA_FILES) "$(DATADIR)"
+	$(INSTALL) -c -m 644 $(DATA_FILES) "$(DATADIR)"
 
 uninstall: uninstall-libs uninstall-headers uninstall-data