debian: Treat aprsc.conf as a conffile again

Since compat level 12, dh_installdeb insists config files may
only live in /etc. There's no nice way to override this any
more with a conffiles config file. Override this to prevent
aprsc.conf getting overwritten on every upgrade.

src/debian/rules

@@ -84,6 +84,8 @@ binary-arch: build install
 #	dh_perl
 #	dh_makeshlibs
 	dh_installdeb
+	# Since compat 12, dh_installdeb insists conffiles may only live in /etc.
+	cat debian/conffiles >> $(CURDIR)/debian/aprsc/DEBIAN/conffiles
 	dh_shlibdeps
 	dh_gencontrol
 	dh_md5sums