VirtualFileSystem::mkdir() relies on resolve_path() returning an error,
since it is only interested in the out_parent passed as a pointer. Since
resolve_path_without_veil returns an error, no process veil validation
is done by resolve_path() in that case. Due to this problem, mkdir()
should use resolve_path_without_veil() and then manually validate if the
parent directory of the to-be-created directory is unveiled with 'c'
permissions.
This fixes a bug where the mkdir syscall would not respect the process
veil at all.
e8f491b01d