dbus: Adjust the location of the jamid binary in the D-Bus service.

This is a follow up to commit 2afa99fd (Install dring to libexec and
edit templates at install time).

* bin/dbus/Makefile.am (do_subst): Replace bindir by libexecdir.

Change-Id: I380e61467ef4f3c4873698c9e2061b9c61370d44

bin/dbus/Makefile.am

@@ -61,7 +61,7 @@ endif
 libclient_dbus_la_CXXFLAGS = $(AM_CXXFLAGS) $(DBUSCPP_CFLAGS)
 
 do_subst = $(SED) \
-	-e 's,[@]bindir[@],$(bindir),g'
+	-e 's,[@]libexecdir[@],$(libexecdir),g'
 
 cx.ring.Ring.service: cx.ring.Ring.service.in Makefile
 	$(do_subst) < $< > $@