Add missing va_end

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2267)

demos/easy_tls/easy-tls.c

@@ -322,6 +322,7 @@ static void tls_errprintf(int flush, void *apparg, const char *fmt, ...)
         va_start(args, fmt);
         n = (sizeof errbuf) - errbuf_i;
         r = vsnprintf(errbuf + errbuf_i, n, fmt, args);
+        va_end(args);
         if (r >= n)
             r = n - 1;
         if (r >= 0) {