[vino] build: Fix syntax error introduced in 27785a2

[Bastien Nocera <hadess src gnome org>]

commit 133bdead0098b44b714b611ea277bb4c2abbc4df
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Wed Aug 31 14:37:43 2016 +0300

    build: Fix syntax error introduced in 27785a2
    
    https://bugzilla.gnome.org/show_bug.cgi?id=766330

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 0999e87..7ca22b9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -266,7 +266,7 @@ AS_IF([test "x$have_ipv6" = "xyes"],
 AC_MSG_RESULT([$have_ipv6])
 
 dnl systemd user unit directory
-PKG_CHECK_EXISTS (systemd,, AC_MSG_ERROR ([systemd development headers not found]))
+PKG_CHECK_EXISTS([systemd],, [AC_MSG_ERROR([systemd development headers not found])])
 AC_ARG_WITH([systemduserunitdir],
            AS_HELP_STRING([--with-systemduserunitdir=DIR], [Directory for systemd user service files]),
            [],