staging/lustre: remove unused request policies.

Client policies do not make much sense to have in client-only code,
so remove all references to everything but fifo.
This also removes lustre/libcfs/heap.c and its header, since it was
only used by certain request policies (crr and orr).

Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>