K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2014-10-31T05:41:27.335543Z
K 7
svn:log
V 354
filedesc: tidy up fdcopy a little bit

Test for file availability by fde_file != NULL instead of fdisused, this is
consistent with similar checks later.

Drop badfileops check. badfileops don't have DFLAG_PASSABLE set, so it was never
reached in practice.

fdiused is now only used in some KASSERTS, so ifdef it under INVARIANTS.

No functional changes.

END