winbindd: Initialize the domain groups member

winbindd: Initialize the domain groups member

==9405== 4 errors in context 1 of 493:
==9405== Conditional jump or move depends on uninitialised value(s)
==9405==    at 0x7507F71: vfprintf (in /lib64/libc-2.12.so)
==9405==    by 0x75C515B: __vasprintf_chk (in /lib64/libc-2.12.so)
==9405==    by 0x2A8728: dbgtext (stdio2.h:199)
==9405==    by 0x22DCBB: winbindd_list_groups_done (winbindd_list_groups.c:127)
==9405==    by 0x6C7F568: _tevent_req_error (tevent_req.c:167)
==9405==    by 0x6C7F568: _tevent_req_error (tevent_req.c:167)
==9405==    by 0x6C7F568: _tevent_req_error (tevent_req.c:167)
==9405==    by 0x3CDAE8: dcerpc_binding_handle_call_done (binding_handle.c:445)
==9405==    by 0x6C7F568: _tevent_req_error (tevent_req.c:167)
==9405==    by 0x6C7F568: _tevent_req_error (tevent_req.c:167)
==9405==    by 0x202701: wbint_bh_raw_call_done (winbindd_dual_ndr.c:139)
==9405==    by 0x6C82C60: tevent_common_loop_timer_delay (tevent_timed.c:341)
==9405==    by 0x6C83CA1: epoll_event_loop_once (tevent_epoll.c:911)
==9405==    by 0x6C822D5: std_event_loop_once (tevent_standard.c:114)
==9405==    by 0x6C7DC3C: _tevent_loop_once (tevent.c:533)
==9405==    by 0x1D8A03: main (winbindd.c:1490)
==9405==  Uninitialised value was created by a heap allocation
==9405==    at 0x4A069EE: malloc (vg_replace_malloc.c:270)
==9405==    by 0x6A71DCA: _talloc_array (in /usr/lib64/libtalloc.so.2.1.5)
==9405==    by 0x22D959: winbindd_list_groups_send (winbindd_list_groups.c:69)
==9405==    by 0x1D76BC: winbind_client_request_read (winbindd.c:647)
==9405==    by 0x23AF2A: wb_req_read_done (wb_reqtrans.c:126)
==9405==    by 0x6C83EA5: epoll_event_loop_once (tevent_epoll.c:728)
==9405==    by 0x6C822D5: std_event_loop_once (tevent_standard.c:114)
==9405==    by 0x6C7DC3C: _tevent_loop_once (tevent.c:533)
==9405==    by 0x1D8A03: main (winbindd.c:1490)

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Autobuild-User(master): Andreas Schneider <asn@cryptomilk.org>
Autobuild-Date(master): Tue Feb 13 00:25:27 CET 2018 on sn-devel-144