ntdll: check for string and stringlength in _wcslwr and _wcsupr

[Octavian Voicu]

2011/9/7 André Hentschel <nerv at dawncrow.de>:
> +    if (!str || !*str) return NULL;
>     return strlwrW( str );

>+    if (!str || !*str) return NULL;
>    return struprW( str );

It seems strange to return NULL when called with an empty, non-NULL
string. Maybe it should be `return str' instead (so it covers both the
NULL and empty cases sensibly), though strlwrW/struprW seems to be
able to cope with zero-length strings as the NULL char is mapped to
NULL.

Octavian