[gdm] build-gui: fix build when xdmcp is disabled

[Ray Strode <halfline src gnome org>]

commit eee37ace9b14284d44eed8049f25ac390a0c1dc1
Author: Ray Strode <rstrode redhat com>
Date:   Tue Aug 16 08:07:50 2016 -0400

    build-gui: fix build when xdmcp is disabled

 Makefile.am |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 7fcfd2b..aeea8b6 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -5,11 +5,15 @@ SUBDIRS =                     \
        common                  \
        daemon                  \
        libgdm                  \
-       chooser                 \
        utils                   \
        po                      \
        tests                   \
        $(NULL)
+
+if XDMCP_SUPPORT
+SUBDIRS += chooser
+endif
+
 if ENABLE_DOCUMENTATION
 SUBDIRS += docs
 endif