[gnome-builder] vala: fix build output when auto and no available

[Christian Hergert <chergert src gnome org>]

commit e3f2531b6745ee989418b7a486e8382667f5451c
Author: Christian Hergert <christian hergert me>
Date:   Mon Sep 28 04:22:45 2015 -0700

    vala: fix build output when auto and no available

 plugins/vala-pack/configure.ac |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/plugins/vala-pack/configure.ac b/plugins/vala-pack/configure.ac
index 6a13a81..aa1def3 100644
--- a/plugins/vala-pack/configure.ac
+++ b/plugins/vala-pack/configure.ac
@@ -10,6 +10,7 @@ AS_IF([test x$enable_vala_pack_plugin != xno],[
                AS_IF([test x$enable_vala_pack_plugin = xyes],[
                        AC_MSG_ERROR([Failed to locate vala. Please install the vala-devel package.])
                ])
+               enable_vala_pack_plugin=no
        ])
 ])