Fix -Wshadow warnings

Checked that it is supported by gcc 4.2.1 (FreeBSD 9).

fixes #240
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 3aa05d5..ce76693 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -1925,7 +1925,7 @@
         if( ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED )
         {
             char vrfy_buf[512];
-            uint32_t flags = mbedtls_ssl_get_verify_result( &ssl );
+            flags = mbedtls_ssl_get_verify_result( &ssl );
 
             mbedtls_x509_crt_verify_info( vrfy_buf, sizeof( vrfy_buf ), "  ! ", flags );