GH-452 Update threads test to avoid crash on exit.

OpenSSL 3.0 added atexit() handler that appears to cause crashes with test
62_threads-ctx_new-deadlock.t.

The test is now updated to initialise OpenSSL libcrypto so that atexit()
handler is not called. As a result, OpenSSL libraries are no longer cleaned up
on exit. This is fine for the test since the process that runs it is already
exiting and the test requires no special cleaning up.

t/local/62_threads-ctx_new-deadlock.t

@@ -16,15 +16,27 @@ if (not can_thread()) {
 
 require threads;
 
-initialise_libssl();
+# OpenSSL 3.0 and later set atexit() handlers in such a way that this
+# test may crash during the default cleanup on exit.  See
+# https://github.com/openssl/openssl/issues/17469 and
+# https://github.com/radiator-software/p5-net-ssleay/issues/452 for
+# more information, including workarounds when OPENSSL_INIT_crypto()
+# is not available in Net::SSLeay.
+#
+# If we need to do OPENSSL_INIT_crypto() call, we must skip the
+# default library initialisation. Otherwise our call to
+# OPENSSL_init_crypto() won't do anything.
+defined &Net::SSLeay::OPENSSL_init_crypto ?
+    Net::SSLeay::OPENSSL_init_crypto(Net::SSLeay::OPENSSL_INIT_NO_ATEXIT(), undef) :
+    initialise_libssl();
 
 my $start_time = time;
 
 #exit the whole program if it runs too long
 threads->new( sub { sleep 20; warn "FATAL: TIMEOUT!"; exit } )->detach;
 
 #print STDERR "Gonna start multi-threading part\n";
-threads->new(\&do_check) for (1..20);
+threads->new(\&do_check) for (1..100);
 
 #print STDERR "Waiting for all threads to finish\n";
 do_sleep(50) while (threads->list());