FIXME: These implementations of the PathAllocCombine functions have several issues:
- pszPathIn or pszMore may be NULL (but not both)
 
- no check if pszMore is fully qualified (if so, it must be directly copied to the output buffer without being combined with pszPathIn.
 
- if pszMore begins with a single backslash it must be combined with only the root of the path pointed to by pszPathIn and there's no code to extract the root of pszPathIn.
 
- the function will crash with some short string lengths of the parameters