ClearFlag clears a wrong flag

```form
L F = 1;
#do i=1,10
  #setflag `i',F
#enddo
clearflag 5;
.sort
#do i=1,9
  #if flag(`i',F)
    #message flag(`i',F) is true
  #else
    #message flag(`i',F) is false
  #endif
#enddo
.end
```
```
~~~flag(1,F) is true
~~~flag(2,F) is true
~~~flag(3,F) is true
~~~flag(4,F) is true
~~~flag(5,F) is true
~~~flag(6,F) is false
~~~flag(7,F) is true
~~~flag(8,F) is true
~~~flag(9,F) is true
```