These tests often cause a timeout and this issue seems specific to the
Windows platforms.
https://github.com/ruby/ruby/actions/runs/3603761925/jobs/6072346738

This doesn't seem to stably work on mswin:
https://github.com/ruby/ruby/actions/runs/3505363753/jobs/5871633211

For CI stability, it generally seems like a bad idea to run druby tests
on Windows, given that it's pretty much unstable on MinGW as well.

It hangs even after a retry
https://github.com/ruby/ruby/runs/7966439530?check_suite_focus=true

We contacted GitHub Suppport about this before, and we concluded that
the problem is on our end. Unfortunately we don't have a bandwidth to
fix this MinGW problem, so until we get to work on it, this should be
just skipped to avoid a sporadic CI timeout.

to try fixing the following error.

http://rubyci.s3.amazonaws.com/opensuseleap/ruby-master/log/20210407T063004Z.log.html.gz
```
[  605/21105] DRbTests::TestDRbSSLAry#test_06_next/home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/lib/drb/drb.rb:1138:in `method_missing': undefined method `regist' for [1, 2, "III", 4, "five", 6]:Array (NoMethodError)
	from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/lib/drb/extserv.rb:21:in `block in initialize'
	from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/.ext/common/monitor.rb:202:in `synchronize'
	from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/.ext/common/monitor.rb:202:in `mon_synchronize'
	from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/lib/drb/extserv.rb:20:in `initialize'
	from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/test/drb/ut_array_drbssl.rb:35:in `new'
	from /home/chkbuild/chkbuild/tmp/build/20210407T063004Z/ruby/test/drb/ut_array_drbssl.rb:35:in `<main>'
 = 100.05 s
```

Here is my analysis:
The test of drb used both `druby://:0` and `druby://localhost:0` for
DRbServer. However, the former listens on IPv4, and the latter does on
IPv6, depending on environments. The port 0 is automatically assigned,
but sometimes the same port is used to both because they are different
protocols (IPv4 and IPv6). In this case, their URIs are resolved to the
completely same one (`druby://localhost:port`), which confuses the
method `DRb.here?` which determines the DRbObject is remote or local.

This changeset uses `druby://localhost:0` consistently.

and /dev/urandom intentionally.  OpenSSL::PKey::RSA.new opens the two
random generators and keeps the file descriptors.

https://github.com/openssl/openssl/blob/93f99b681ab5a1cf7062053323e09b0cad5ff854/crypto/rand/rand_unix.c#L674

They are detected by the LeakChecker as fd leak, but it is intentional.

http://rubyci.s3.amazonaws.com/graviton2/ruby-master/log/20200526T160005Z.log.html.gz
```
[  597/20199] DRbTests::TestDRbSSLAry#test_01 = 0.29 s
Leaked file descriptor: DRbTests::TestDRbSSLAry#test_01: 8 #<File::Stat dev=0x6, ino=11, mode=020666, nlink=1, uid=0, gid=0, rdev=0x109, size=0, blksize=4096, blocks=0, atime=2020-05-23 14:45:13.751999995 +0000, mtime=2020-05-23 14:45:13.751999995 +0000, ctime=2020-05-23 14:45:13.751999995 +0000>
Leaked file descriptor: DRbTests::TestDRbSSLAry#test_01: 9 #<File::Stat dev=0x6, ino=10, mode=020666, nlink=1, uid=0, gid=0, rdev=0x108, size=0, blksize=4096, blocks=0, atime=2020-05-23 14:45:13.755999995 +0000, mtime=2020-05-23 14:45:13.755999995 +0000, ctime=2020-05-23 14:45:13.755999995 +0000>
```

This reverts commit 3be3948870f6589343c4aecb541e22fae7751b47.

The Solaris environment couldn't lookup the hostname itself by a wrong
setting.  Now it is fixed, so try again.

This reverts commit 84dca8eff0cbcb1c23623b47fb78b0daf5c76e35.

"exceution expired" occurred on Solaris.
https://rubyci.org/logs/rubyci.s3.amazonaws.com/solaris11s-sunc/ruby-master/log/20190901T072504Z.fail.html.gz

This reverts commit 8adefd4cf29288f6e43f20efbdd44b215ae16c7a.

I couldn't see any failure on Solaris if the guard is removed.
Give it a try.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65333 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Do not start background thread on load test/drb/drbtest.rb,
and stop threads on each test.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65247 b2dd03c8-39d4-4d8f-98ff-823fe69b080e