Merge development commit 8e76332 into development-psa

Additional changes to temporarily enable running tests:
ssl_srv.c and test_suite_ecdh use mbedtls_ecp_group_load instead of
mbedtls_ecdh_setup
test_suite_ctr_drbg uses mbedtls_ctr_drbg_update instead of 
mbedtls_ctr_drbg_update_ret
diff --git a/library/x509_crt.c b/library/x509_crt.c
index c5b6a12..3a3c0a0 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -2203,7 +2203,7 @@
     }
 
     /* extra precaution against mistakes in the caller */
-    if( parent == NULL )
+    if( *parent == NULL )
     {
         *parent_is_trusted = 0;
         *signature_is_good = 0;