[gxml] Update libvala version; need a better solution to this

[Richard Hans Schwarting <rschwart src gnome org>]

commit 11420efc2dfbce4600ce6c7cc37a6bcf031ab1e4
Author: Richard Schwarting <aquarichy gmail com>
Date:   Sat Jul 27 00:00:18 2013 -0400

    Update libvala version; need a better solution to this

 configure.ac |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 6828532..7d68f1a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -105,9 +105,11 @@ AC_SUBST([API_VERSION])
 
 ### Dependencies
 
+# TODO: what do we do about libvala's versioning?  set it back to -0.18 and see what happens when we 
upgraded from Fedora 18 to 19
+
 GLIB_REQUIRED=2.16.0
 VALA_REQUIRED=0.16.0
-VALA_MODULES="libvala-0.18 >= 0.16"
+VALA_MODULES="libvala-0.20 >= 0.16"
 GEE_REQUIRED=0.7.0
 LIBXML_REQUIRED=2.7
 GIO_MODULES="gio-2.0 >= 2.16"