fusefs: handle evil servers that return illegal inode numbers

fusefs: handle evil servers that return illegal inode numbers

* If during FUSE_CREATE, FUSE_MKDIR, etc the server returns the same
  inode number for the new file as for its parent directory, reject it.
  Previously this would triggers a recurse-on-non-recursive lock panic.

* If during FUSE_LINK the server returns a different inode number for
  the new name as for the old one, reject it.  Obviously, that can't be
  a hard link.

* If during FUSE_LOOKUP the server returns the same inode number for the
  new file as for its parent directory, reject it.  Nothing good can
  come of this.

PR:		263662
Reported by:	Robert Morris <rtm@lcs.mit.edu>
MFC after:	2 weeks
Reviewed by:	pfg
Differential Revision: https://reviews.freebsd.org/D35128