[gegl] configure: depend on babl 0.1.39 or newer

[Øyvind Kolås <ok src gnome org>]

commit 0c97ed1e087da192b6491b48e69b0996d3bf99d1
Author: Øyvind Kolås <pippin gimp org>
Date:   Sat Jan 13 13:25:35 2018 +0100

    configure: depend on babl 0.1.39 or newer

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index efa1431..292e7f2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -37,7 +37,7 @@ m4_define([gegl_stable],
 m4_define([gimp_full_name], [Generic Graphical Library])
 
 # required versions of external libraries
-m4_define([babl_required_version], [0.1.38])
+m4_define([babl_required_version], [0.1.39])
 m4_define([cairo_required_version], [1.12.2])
 m4_define([exiv2_required_version], [0.25])
 m4_define([gdk_pixbuf_required_version], [2.32.0])