Refactor set_ciphersuites to work on the endpoint structure

Link the ciphersuite list that's passed to mbedtls_ssl_conf_ciphersuites(),
and needs to survive in memory as long as the configuration object is live,
in the endpoint structure. This way it doesn't have to be a local variable
in mbedtls_test_ssl_do_handshake_with_endpoints().

Signed-off-by: Gilles Peskine <[email protected]>

tests/include/test/ssl_helpers.h

@@ -199,6 +199,7 @@ typedef struct mbedtls_test_ssl_endpoint {
 #endif
 
     /* Objects owned by the endpoint */
+    int *ciphersuites;
     mbedtls_x509_crt *ca_chain;
     mbedtls_x509_crt *cert;
     mbedtls_pk_context *pkey;