Ingore TSAN errors accessing 'last'

Ingore TSAN errors accessing 'last'

    WARNING: ThreadSanitizer: data race
    Read of size 4 at 0x000000000001 by thread T1:
    #0 log_quota bin/named/query.c:4291:22
    #1 query_recurse bin/named/query.c:4346:4
    #2 query_find bin/named/query.c
    #3 ns_query_start bin/named/query.c:9716:8
    #4 client_request bin/named/client.c:3115:3
    #5 dispatch lib/isc/task.c:1157:7
    #6 run lib/isc/task.c:1331:2

    Previous write of size 4 at 0x000000000001 by thread T2:
    #0 last_cmpxchg bin/named/query.c:81:6
    #1 log_quota bin/named/query.c:4293:7
    #2 query_recurse bin/named/query.c:4346:4
    #3 query_find bin/named/query.c
    #4 ns_query_start bin/named/query.c:9716:8
    #5 client_request bin/named/client.c:3115:3
    #6 dispatch lib/isc/task.c:1157:7
    #7 run lib/isc/task.c:1331:2