Fix -Wmisleading-indentation complaint

New in gcc 6:

  comms.c: In function ‘json_escape’:
  comms.c:337:8: error: this ‘else’ clause does not guard... [-Werror=misleading-indentation]
         }else
          ^~~~
  comms.c:338:32: note: ...this statement, but the latter is misleadingly
  indented as if it is guarded by the ‘else’
        mws_add(line, "%c", *in); break;
                                  ^~~~~
  cc1: all warnings being treated as errors