[gnome-code-assistance] configure.ac: Add vala 0.40 to list of possible vala APIs

[Tristan Van Berkom <tvb src gnome org>]

commit f20cc482ee2112ccd2acc792834be3c74439629f
Author: Tristan Van Berkom <tristan vanberkom codethink co uk>
Date:   Thu Oct 26 15:50:03 2017 +0900

    configure.ac: Add vala 0.40 to list of possible vala APIs
    
    GNOME 3.27 is now building vala 0.40, which means older versions
    of vala are not present for a clean build and this causes
    gnome-code-assistance to fail to build.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 8b0fda0..9056227 100644
--- a/configure.ac
+++ b/configure.ac
@@ -410,7 +410,7 @@ AC_ARG_ENABLE([vala],
               [enable_vala=$enableval],
               [enable_vala=auto])
 
-BACKEND_VALA_LIBVALA_VERSIONS="libvala-0.38 libvala-0.36 libvala-0.34 libvala-0.32 libvala-0.30 libvala-0.28 
libvala-0.26 libvala-0.24 libvala-0.22 libvala-0.20"
+BACKEND_VALA_LIBVALA_VERSIONS="libvala-0.40 libvala-0.38 libvala-0.36 libvala-0.34 libvala-0.32 libvala-0.30 
libvala-0.28 libvala-0.26 libvala-0.24 libvala-0.22 libvala-0.20"
 BACKEND_VALA_MODULES="gobject-2.0 >= 2.36 glib-2.0 >= 2.36 gio-2.0 >= 2.36 gee-0.8 gio-unix-2.0 >= 2.36"
 
 BACKEND_VALA_LIBVALA=