Moved wine_get_unix_file_name implementation to ntdll, and changed it
to return an allocated buffer instead of a fixed size one.

diff --git a/include/winbase.h b/include/winbase.h
index 9c7fcc6..50fb61b 100644
--- a/include/winbase.h
+++ b/include/winbase.h
@@ -1988,7 +1988,7 @@
 
 /* Wine internal functions */
 
-BOOL        WINAPI wine_get_unix_file_name( LPCWSTR dos, LPSTR buffer, DWORD len );
+extern char *wine_get_unix_file_name( LPCWSTR dos );
 
 
 /* a few optimizations for i386/gcc */