[gdm] data: remove stray -n passed to test

[Ray Strode <halfline src gnome org>]

commit d2e24d6dab81626e7befce9e056bd2fcce162791
Author: Ray Strode <rstrode redhat com>
Date:   Wed Apr 19 13:51:47 2017 -0400

    data: remove stray -n passed to test

 data/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/data/Makefile.am b/data/Makefile.am
index cb7c4cf..d011134 100644
--- a/data/Makefile.am
+++ b/data/Makefile.am
@@ -309,7 +309,7 @@ endif
                chown root:gdm $(DESTDIR)$(xauthdir) || : ; \
        fi
 
-       if test -n '!' -d $(DESTDIR)$(SYSTEMD_SYSTEM_UNIT_DIR); then \
+       if test '!' -d $(DESTDIR)$(SYSTEMD_SYSTEM_UNIT_DIR); then \
                $(mkinstalldirs) $(DESTDIR)$(SYSTEMD_SYSTEM_UNIT_DIR); \
                chmod 0755 $(DESTDIR)$(SYSTEMD_SYSTEM_UNIT_DIR); \
                chown root:root $(DESTDIR)$(SYSTEMD_SYSTEM_UNIT_DIR) || : ; \