kernel32: CreateDirectory shouldn't return ERROR_ACCESS_DENIED for the root of the...

kernel32: CreateDirectory shouldn't return ERROR_ACCESS_DENIED for the root of the drive.

According to the testbot results CreateDirectory("C:\\", NULL) fails
with ERROR_ACCESS_DENIED for not administrators. However with UAC enabled
and not and administrator account I get ERROR_ALREADY_EXISTS in that case
with Windows 7 64-bit running on real hardware. Moreover, Wine doesn't
really perform any access checks in that case and blindly assumes that
returning STATUS_ACCESS_DENIED is correct behaviour for the drive's root:
dlls/ntdll/directory.c,lookup_unix_name().

This patch fixes an application that can't find its data files because
after it receives ERROR_ACCESS_DENIED it stops further directory traversing.

Signed-off-by: Dmitry Timoshkov <dmitry@baikal.ru>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>