criu: don't leak a service fd

Recently, I introduced a new mode when a service fd are not dupped into
a fixed file descriptor number. A side effect of this is that we need to
close the old descritpor if it was installed.

Fixes: d3499999 ("criu: remove all magic of service-fd when it isn't required")

criu/util.c

@@ -495,6 +495,8 @@ int install_service_fd(enum sfd_type type, int fd)
 		sfds_protection_bug(type);
 
 	if (service_fd_base == 0) {
+		if (test_bit(type, sfd_map))
+			close(sfd_arr[type]);
 		sfd_arr[type] = fd;
 		set_bit(type, sfd_map);
 		return fd;