Ports: Fix reinstalling the mysthous port

Reinstalling the port failed because some of its files were installed
with permissions that prevented overwriting the existing files with cp.

Ports/mysthous/package.sh

@@ -27,5 +27,6 @@ post_fetch() {
 install() {
     target_dir="${SERENITY_INSTALL_ROOT}${resource_path}"
     run_nocd mkdir -p ${target_dir}
+    run_nocd chmod 644 ${workdir}/*
     run_nocd cp ${workdir}/MYSTHOUS.DSK ${target_dir}
 }