'RELENG_6_0_0_RELEASE'.

This commit was manufactured to restore the state of the 6.0-RELEASE image.

- bzipfs and gzipfs now properly return errno values directly from their
  read routines rather than returning -1.
- missing errno values on error returns for the seek routines on almost
  all filesystems were added.
- fstat() now returns -1 if an error occurs rather than ignoring it.
- nfs's readdir() routine now reports valid errno values if an error or
  EOF occurs rather than EPERM  (It was just returning 0 for success and
  1 for failure).
- nullfs used the wrong semantics for every function besides close() and
  seek().  Getting it right for close() appears to be an accident at that.
- read() for buffered files no longer returns 0 (EOF) if an error occurs,
  but returns -1 instead.

functionality for some of the filesystesms.

	o use braces to avoid potentially ambiguous else
	o don't default to type int (and also remove a useless register
	  modifier).
	o Use parens around assignment values used as truth values.
	o Remove unused function.

Reviewed by: obrien and chuckr

(FAT12/16/32, VFAT).

Make a private copy of strcasecmp, as the "real" one uses the system ctype
header, which introduces locale poisoning.

Sort out fs_ops, alloc/free.

modules).
Obtained from: NetBSD, with some architectural changes and many additions.