Fix to GRES NoConsume logic

we came across the following error message in the slurmctld logs when
using non-consumable resources:

error: gres/potion: job 39 dealloc of node node1 bad node_offset 0 count
is 0

The error comes from _job_dealloc():

node_gres_data=0x7f8a18000b70, node_offset=0, gres_name=0x1999e00
"potion", job_id=46,
    node_name=0x1987ab0 "node1") at gres.c:3980
(job_gres_list=0x199b7c0, node_gres_list=0x199bc38, node_offset=0,
job_id=46,
    node_name=0x1987ab0 "node1") at gres.c:4190
job_ptr=0x19e9d50, pre_err=0x7f8a31353cb0 "_will_run_test", remove_all=true)
    at select_linear.c:2091
bitmap=0x7f8a18001ad0, min_nodes=1, max_nodes=1, max_share=1, req_nodes=1,
    preemptee_candidates=0x0, preemptee_job_list=0x7f8a2f910c40) at
select_linear.c:3176
bitmap=0x7f8a18001ad0, min_nodes=1, max_nodes=1, req_nodes=1, mode=2,
    preemptee_candidates=0x0, preemptee_job_list=0x7f8a2f910c40,
exc_core_bitmap=0x0) at select_linear.c:3390
bitmap=0x7f8a18001ad0, min_nodes=1, max_nodes=1, req_nodes=1, mode=2,
    preemptee_candidates=0x0, preemptee_job_list=0x7f8a2f910c40,
exc_core_bitmap=0x0) at node_select.c:588
avail_bitmap=0x7f8a2f910d38, min_nodes=1, max_nodes=1, req_nodes=1,
exc_core_bitmap=0x0)
    at backfill.c:367

The cause of this problem is that _node_state_dup() in gres.c does not
duplicate the no_consume flag.
The cr_ptr passed to _rm_job_from_nodes() is created with _dup_cr()
which calls _node_state_dup().

Below is a simple patch to fix the problem. A "future-proof" alternative
might be to memcpy() from gres_ptr to new_gres and
only handle pointers separately.