make use of mv's backup feature so that calling the ca-bundle target more than...

make use of mv's backup feature so that calling the ca-bundle target more than once will never fail; ignore error which can occure if for whatever reason there's no orignial ca-bundle.crt to rename.

Makefile.am

@@ -134,5 +134,5 @@ uninstall-hook:
 
 ca-bundle: lib/mk-ca-bundle.pl
 	@echo "generate a fresh ca-bundle.crt"
-	@mv lib/ca-bundle.crt lib/ca-bundle.crt.old
+	@-mv -vbVt lib/ca-bundle.crt lib/ca-bundle.crt.old
 	@perl $< -l -u lib/ca-bundle.crt

Makefile.dist

@@ -263,7 +263,7 @@ vc8:
 
 ca-bundle: lib/mk-ca-bundle.pl
 	@echo "generate a fresh ca-bundle.crt"
-	@mv -v lib/ca-bundle.crt lib/ca-bundle.crt.old
+	@-mv -vbVt lib/ca-bundle.crt lib/ca-bundle.crt.old
 	@perl $< -l -u lib/ca-bundle.crt