Check CMSIS-DAP adapter has serialnumber before pass it to wcscmp.
Keep looking for onother adapter if choosed one doesn't have correct
serialnumber.
Change-Id: I7d386a03cb49b9baf22073ae1c6b14269ed3b618
Signed-off-by: Andrii Anpilogov <anpilog@gmail.com>
Reviewed-on: http://openocd.zylin.com/3226
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>
                        /* we have found an adapter, so exit further checks */
                        /* check serial number matches if given */
                        if (cmsis_dap_serial != NULL) {
-                               if (wcscmp(cmsis_dap_serial, cur_dev->serial_number) == 0) {
+                               if ((cur_dev->serial_number != NULL) && wcscmp(cmsis_dap_serial, cur_dev->serial_number) == 0) {
                                        serial_found = true;
                                        break;
                                }
                        } else
                                break;
+
+                       found = false;
                }
 
                cur_dev = cur_dev->next;