kernel32: Implement ReplaceFileA/ReplaceFileW

[Felix Nawothnig]

Erich Hoover wrote:
> Real Name:
>     Erich Hoover
> Description:
>     Implements the functions ReplaceFileA and ReplaceFileW in kernel32 
> (Bug #7544).  Also provides conformance test code to ensure proper 
> functionality.
> Changelog:
>     kernel32: Implement ReplaceFileA/ReplaceFileW

Your patch seems to introduce lots of race cons. It's possible these 
exist on Win32 too but can't we avoid them?