winspool: GetPrinterDriverDirectory updated to NT/win9x (resend)

[Detlef Riekenberg]

Resend with suggestions from Alexandre:
 GetVersion() was used to often.

- We do not Check for WIN32S.
- For Win9x, we use the same Path as NT is using for "Windows 4.0"
  (%winsysdir%\spool\drivers\win40)

Changelog:
 - Add Function "validate_envW" to validate the user-supplied
   Printing Environment (respect "Windows Version" - Setting)
 - Change GetPrinterDriverDirectoryW on top of "validate_envW" 
   to Report the native Path for NT and Win9x
 - Fix 2 Bugs in GetPrinterDriverDirectoryA
 - 2 Tests are now working in Wine

"validate_envW" will be used by more Functions later.
(WINSPOOL_OpenDriverReg as Example)