Add accept as an accepted value through syscall()

This commit adds the accept(2) value to syscall(2) so we can pass it on
to Tor and not deny it blindly.

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Test: fix memory leak in DNS test

Fix Coverity issue 1243012.

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Test: possible double free in onion test

Fix Coverity issue 1195191.

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Test: add missing connection destroy

Signed-off-by: David Goulet <dgoulet@ev0ke.net>