Those files don't contain any @variables@, so the configuration step was just
copying them to build/. Let's avoid that, and fix their suffixes while at it.
# install_dir : dbuspolicydir)
# install_data('org.freedesktop.login1.service',
# install_dir : dbussystemservicedir)
-#
-# policy = configure_file(
-# input : 'org.freedesktop.login1.policy.in',
-# output : 'org.freedesktop.login1.policy',
-# configuration : substs)
-# install_data(policy,
+# install_data('org.freedesktop.login1.policy',
# install_dir : polkitpolicydir)
#
# install_data('70-power-switch.rules', install_dir : udevrulesdir)