Add test exercising context-specific CRT callback to ssl-opt.sh
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 8800cc7..e030195 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -6059,11 +6059,13 @@
 
     if( ssl->f_vrfy != NULL )
     {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "Use context-specific verification callback" ) );
         f_vrfy = ssl->f_vrfy;
         p_vrfy = ssl->p_vrfy;
     }
     else
     {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "Use configuration-specific verification callback" ) );
         f_vrfy = ssl->conf->f_vrfy;
         p_vrfy = ssl->conf->p_vrfy;
     }