Merge pull request #5730 from gilles-peskine-arm/ssl-opt-auto-psk-2.28

Backport 2.28: Run ssl-opt.sh in more reduced configurations

library/ssl_tls.c

@@ -990,6 +990,7 @@ static int ssl_populate_transform( mbedtls_ssl_transform *transform,
 
 #if !defined(MBEDTLS_SSL_HW_RECORD_ACCEL) && \
     !defined(MBEDTLS_SSL_EXPORT_KEYS) && \
+    !defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
     !defined(MBEDTLS_DEBUG_C)
     ssl = NULL; /* make sure we don't use it except for those cases */
     (void) ssl;