Refactor macro-spanning if in ssl_tls12_client.c

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/library/ssl_tls12_client.c b/library/ssl_tls12_client.c
index d1ec55c..ba39d89 100644
--- a/library/ssl_tls12_client.c
+++ b/library/ssl_tls12_client.c
@@ -2471,9 +2471,11 @@
 
         if( ret != 0 )
         {
+            int send_alert_msg = 1;
 #if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
-            if( ret != MBEDTLS_ERR_ECP_IN_PROGRESS )
+            send_alert_msg = ( ret != MBEDTLS_ERR_ECP_IN_PROGRESS );
 #endif
+            if( send_alert_msg )
                 mbedtls_ssl_send_alert_message(
                     ssl,
                     MBEDTLS_SSL_ALERT_LEVEL_FATAL,