base: preserve exec attr on /etc/cron.hourly/sysupdate

when testing upcoming changes on a live node, it is desirable to turn
off automatic updates simply by removing the x file permissions bit.
this commit makes sure the x bit is set only for newly created file.

base/voidlinux.sh

@@ -13,9 +13,9 @@ if [ ! -f /etc/cron.hourly/sysupdate ]; then
 #!/bin/sh
 exec /ssd/sysupdates/update.sh
 EOF
+        chmod +x /etc/cron.hourly/sysupdate
     fi
 fi
-chmod +x /etc/cron.hourly/sysupdate
 
 # install required packages and config files
 set -e