s4:torture:rpc: fix valgrind Syscall param writev(vector[...]) error

s4:torture:rpc: fix valgrind Syscall param writev(vector[...]) error

running smbtorture rpc.srvsvc.srvsvc\ (admin\ access).NetDiskEnum results
in the following valgrind trace

==30237== Syscall param writev(vector[...]) points to uninitialised byte(s)
==30237==    at 0xDD01C67: writev (in /lib64/libc-2.19.so)
==30237==    by 0xE1D09D4: writev_handler (async_sock.c:340)
==30237==    by 0xD81A12A: ??? (in /usr/lib64/libtevent.so.0.9.26)
==30237==    by 0xD8185F6: ??? (in /usr/lib64/libtevent.so.0.9.26)
==30237==    by 0xD8147FC: _tevent_loop_once (in /usr/lib64/libtevent.so.0.9.26)
==30237==    by 0xD815ACE: tevent_req_poll (in /usr/lib64/libtevent.so.0.9.26)
==30237==    by 0x5AC726D: tevent_req_poll_ntstatus (in /usr/lib64/libtevent-util.so.0.0.1)
==30237==    by 0x8120CEA: dcerpc_binding_handle_call (in /usr/lib64/libdcerpc-binding.so.0.0.1)
==30237==    by 0xA9AC6EC: dcerpc_srvsvc_NetDiskEnum_r (ndr_srvsvc_c.c:5388)
==30237==    by 0x2ADDF8: ??? (in /usr/bin/smbtorture)
==30237==    by 0x898DF8C: ??? (in /usr/lib64/libtorture.so.0.0.1)
==30237==    by 0x1F0816: ??? (in /usr/bin/smbtorture)
==30237==  Address 0x15952676 is 598 bytes inside a block of size 1,325 alloc'd
==30237==    at 0x4C29110: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==30237==    by 0xCCCAA73: _talloc_pooled_object (in /usr/lib64/libtalloc.so.2.1.5)
==30237==    by 0xD81566D: _tevent_req_create (in /usr/lib64/libtevent.so.0.9.26)
==30237==    by 0xA2B7910: smb1cli_req_create (smbXcli_base.c:1322)
==30237==    by 0xA2BA4E3: smb1cli_trans_send (smb1cli_trans.c:512)
==30237==    by 0xA2C1F91: tstream_smbXcli_np_readv_trans_start (tstream_smbXcli_np.c:901)
==30237==    by 0xA2C23AE: tstream_smbXcli_np_writev_send (tstream_smbXcli_np.c:505)
==30237==    by 0xAC8E43C: tstream_writev_send (tsocket.c:695)
==30237==    by 0xAC8E9BA: tstream_writev_queue_trigger (tsocket_helpers.c:513)
==30237==    by 0xD815023: tevent_common_loop_immediate (in /usr/lib64/libtevent.so.0.9.26)

Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>