Ensure /var/run/ld-elf.so.hints exists before building

pkg(8).

MFC after:	3 days
X-MFC-With:	r276820
Sponsored by:	The FreeBSD Foundation

release/scripts/pkg-stage.sh

@@ -40,6 +40,7 @@ if [ ! -f /usr/ports/Makefile ]; then
 fi
 
 if [ ! -x /usr/local/sbin/pkg ]; then
+	/etc/rc.d/ldconfig restart
 	/usr/bin/make -C /usr/ports/ports-mgmt/pkg install clean
 fi