shlwapi: implement StrChrNW

[Nikolay Sivov]

Aric Stewart wrote:
> ---
>  dlls/shlwapi/shlwapi.spec |    1 +
>  dlls/shlwapi/string.c     |   23 +++++++++++++++++++++++
>  2 files changed, 24 insertions(+), 0 deletions(-)
Maybe it's better to move this
---
+@ stdcall StrChrNW(wstr long long)
---
closer to context:
---
@ stdcall StrChrA (str long)
@ stdcall StrChrIA (str long)
@ stdcall StrChrIW (wstr long)
@ stdcall StrChrW (wstr long)
---
to keep it consistent.