Merge from NetBSD:

Merge from NetBSD:
Fix a problem in previous: we can't blindly assume that we have
wincnt entries available at the offset the file has been found. If the dos
directory entry is not preceded by appropriate number of long name
entries (happens e.g. when the filesystem is corrupted, or when
the filename complies to DOS rules and doesn't use any long name entry),
we would overwrite random directory entries.

There are still some problems, the whole thing has to be revisited and solved
right.

Submitted by:	Xin LI