https://github.com/GNOME/gdm/commit/eee5bf72c9bb1c1d62eb0e7102088ae3b9a188cd
--- a/configure.ac	2016-05-27 11:10:44.589740789 +0200
+++ b/configure.ac	2016-05-27 11:11:00.146427723 +0200
@@ -888,7 +888,7 @@
 dnl ---------------------------------------------------------------------------
 
 PKG_CHECK_MODULES(SYSTEMD,
-                  [libsystemd-login >= 186 libsystemd-daemon],
+                  [libsystemd],
                   [have_systemd=yes], [have_systemd=no])
 
 if test "x$with_systemd" = "xauto" ; then
@@ -912,7 +912,7 @@
 AC_SUBST(SYSTEMD_LIBS)
 
 PKG_CHECK_MODULES(JOURNALD,
-                  [libsystemd-journal],
+                  [libsystemd],
                   [have_journald=yes], [have_journald=no])
 
 if test "x$enable_systemd_journal" = "xauto" ; then