[PATCH] ntdll: implement RtlCreateRegistryKey

[Nikolay Sivov]

Could you please add some tests for that one? It's interesting to verify 
what happens if specified path contains keys that don't exist yet. 
According to docs it should only create last part, and the rest of the 
path is supposed to exist already. Also some tests for argument 
validation are easy to have, like invalid first argument, or empty/NULL 
second one.