Add debug message

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index a6e4e38..140b749 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -8179,6 +8179,9 @@
 
     for( ; *sig_alg != MBEDTLS_TLS1_3_SIG_NONE; sig_alg++ )
     {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "got signature scheme [%x] %s",
+                                    *sig_alg,
+                                    mbedtls_ssl_sig_alg_to_str( *sig_alg ) ) );
         if( ! mbedtls_ssl_sig_alg_is_supported( ssl, *sig_alg ) )
             continue;
         MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );