Missing lookup in msvcr120 for pgwin32_putenv

Hi all,

While looking at e545281 I bumped into the following thing that has
visibly been forgotten since VS2013 support has been added:
--- a/src/port/win32env.c
+++ b/src/port/win32env.c
@@ -67,6 +67,9 @@ pgwin32_putenv(const char *envval)
            "msvcr110", 0, NULL
        },                      /* Visual Studio 2012 */
        {
+           "msvcr120", 0, NULL
+       },                      /* Visual Studio 2013 */
+       {
            NULL, 0, NULL
        }
    };

Attached is a patch. This should be backpatched to 9.3 where, if I
recall correctly, support for VS2013 has been added.
Regards,
--
Michael