consistently use %{_unitdir} macro

avahi.spec

@@ -18,7 +18,7 @@
 
 Name:             avahi
 Version:          0.7
-Release:          4%{?dist}
+Release:          5%{?dist}
 Summary:          Local network service discovery
 License:          LGPLv2+
 URL:              http://avahi.org
@@ -356,7 +356,7 @@ NOCONFIGURE=1 ./autogen.sh
         --with-avahi-priv-access-group=avahi \
         --with-autoipd-user=avahi-autoipd \
         --with-autoipd-group=avahi-autoipd \
-        --with-systemdsystemunitdir=/usr/lib/systemd/system \
+        --with-systemdsystemunitdir=%{_unitdir} \
         --enable-introspection=no \
 %if %{WITH_COMPAT_DNSSD}
         --enable-compat-libdns_sd \
@@ -661,6 +661,9 @@ exit 0
 
 
 %changelog
+* Sat Oct 07 2017 Rex Dieter <rdieter@fedoraproject.org> - 0.7-5
+- consistently use %%{_unitdir} macro
+
 * Mon Oct 02 2017 Troy Dawson <tdawson@redhat.com> - 0.7-4
 - Cleanup spec file conditionals