selftest: Fix memset parameters in test for async_connect_send()

selftest: Fix memset parameters in test for async_connect_send()

This fixes:

../lib/async_req/async_connect_send_test.c: In function ‘main’:
../lib/async_req/async_connect_send_test.c:88:3: error: ‘memset’ used with constant zero length parameter; this could be due to transposed parameters [-Werror=memset-transposed-args]
   memset(&addr, sizeof(addr), 0);
   ^
Bug: https://bugzilla.samba.org/show_bug.cgi?id=11564

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Autobuild-User(master): Ralph Böhme <slow@samba.org>
Autobuild-Date(master): Wed Oct 21 17:31:00 CEST 2015 on sn-devel-104