c/10339: strncmp generates imPure code

[Hans-Peter Nilsson]

On 7 Apr 2003, Falk Hueffner wrote:
> This optimiziation would only be invalid if
>
> * it gives a different result,
> * or the memory read straddles a page boundary and faults.

Or
  * you use a tool such as valgrind to execute the code
    (a variant of the first item).

(yeah, yeah, this wasn't about i*86...  Replace "valgrind"
with "purify"  or similar.)

brgds, H-P