scons: require scons 2.4 or greater
There is a bug with scons 2.3, used in Travis, where it fails to detect
some C functions.
Reviewed-by: Andres Gomez <agomez@igalia.com>
diff --git a/SConstruct b/SConstruct
index a59a8ea..6e034fb 100644
--- a/SConstruct
+++ b/SConstruct
@@ -28,6 +28,12 @@
import common
#######################################################################
+# Minimal scons version
+
+EnsureSConsVersion(2, 4)
+
+
+#######################################################################
# Configuration options
opts = Variables('config.py')