HAVE_POLKIT seems unused

Version information

4.19.3 I'm packaging it for Gentoo

Steps to reproduce

grep -R HAVE_POLKIT

Current behavior

I've noticed that thunar 4.19.3 adds a check for optional polkit package. However, it doesn't seem that the result of the check is actually used anywhere. FWICS, the only mention of HAVE_POLKIT in Makefiles (and source code) is:

# Not using HAVE_POLKIT because a lot of distributions put
# polkit.{its,loc} in binary package instead of development package.
# E.g. Debian puts in polkitd instead of libpolkit-gobject-1-dev

Expected outcome

I'd like to ask for clarification whether having polkit or not actually changes anything at build time.