Fix failure for ipv6 not enabled

In case of ipv6 not enabled tests like `main.ipv6, rpl.rpl_ipv6` failed on
aarch buildbot.
Fix it by following commits 70dcb46e and 0bae1957 for
`10.2`.

mysql-test/mysql-test-run.pl

@@ -269,7 +269,7 @@ my $current_config_name; # The currently running config file template
 our @opt_experimentals;
 our $experimental_test_cases= [];
 
-my $baseport;
+our $baseport;
 # $opt_build_thread may later be set from $opt_port_base
 my $opt_build_thread= $ENV{'MTR_BUILD_THREAD'} || "auto";
 my $opt_port_base= $ENV{'MTR_PORT_BASE'} || "auto";

mysql-test/suite.pm

@@ -33,9 +33,10 @@ sub skip_combinations {
   sub ipv6_ok() {
     use Socket;
     return 0 unless socket my $sock, PF_INET6, SOCK_STREAM, getprotobyname('tcp');
+    $!="";
     # eval{}, if there's no Socket::sockaddr_in6 at all, old Perl installation
-    eval { connect $sock, sockaddr_in6(7, Socket::IN6ADDR_LOOPBACK) };
-    return $@ eq "";
+    eval { bind $sock, sockaddr_in6($::baseport, Socket::IN6ADDR_LOOPBACK) };
+    return $@ eq "" && $! eq ""
   }
   $skip{'include/check_ipv6.inc'} = 'No IPv6' unless ipv6_ok();