* SConstruct: Allow VC 14.2 (VC 2019), as 15.0 doesn't exist yet.

git-svn-id: https://svn.apache.org/repos/asf/serf/trunk@1861036 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/SConstruct b/SConstruct
index dc405c4..9d0fc91 100644
--- a/SConstruct
+++ b/SConstruct
@@ -154,7 +154,7 @@
     EnumVariable('MSVC_VERSION',
                  "Visual C++ to use for building",
                  None,
-                 allowed_values=('15.0', '14.1', '14.0', '12.0',
+                 allowed_values=('14.2', '14.1', '14.0', '12.0',
                                  '11.0', '10.0', '9.0', '8.0', '6.0'),
                  map={'2005' :  '8.0',
                       '2008' :  '9.0',