Fix tests for JRuby

Well, "fix" might overstate it, but we were able to get them passing
by backporting test skips that are currently in Puma master upstream.

With these skips, not only does tag `4.3.3.` all pass, but so does
our custom branch, so we can be pretty confident we haven't broken
anything vs. stock Puma.

Some notes on test runs:
- Invoke with `bundle exec rake test --trace`
- Ctrl-C'ing the tests usually left a zombified version running in the
background, which would *cause failures on subsequent runs*.  Ensure
after killing the a test run that no test processes remain in `jps -lm`
- `TestThreadPool` tests are flaky in this release, though this was a
known issue, and has been recently fixed here: puma#2220

test/test_cli.rb

@@ -66,6 +66,7 @@ def test_control_for_tcp
   end
 
   def test_control_for_ssl
+    skip_on :jruby # backported from https://github.com/puma/puma/blob/b0b17f6ffd6a3fc858202a2b0ac1385f45603b18/test/test_cli.rb#L67
     app_port = UniquePort.call
     control_port = UniquePort.call
     control_host = "127.0.0.1"
@@ -97,8 +98,8 @@ def test_control_for_ssl
     assert_match(expected_stats, Puma.stats)
 
   ensure
-    cli.launcher.stop
-    t.join
+    cli.launcher.stop if cli
+    t.join if t
   end
 
   def test_control_clustered

test/test_launcher.rb

@@ -5,6 +5,7 @@
 class TestLauncher < Minitest::Test
   def test_dependencies_and_files_to_require_after_prune_is_correctly_built_for_no_extra_deps
     skip_on :no_bundler
+    skip_on :jruby, suffix: " - customizing puma.gemspec to disable the C native extension invalidates this test"
 
     deps, dirs = launcher.send(:dependencies_and_files_to_require_after_prune)
 
@@ -17,6 +18,7 @@ def test_dependencies_and_files_to_require_after_prune_is_correctly_built_for_no
   end
 
   def test_dependencies_and_files_to_require_after_prune_is_correctly_built_with_extra_deps
+    skip_on :jruby, suffix: " - customizing puma.gemspec to disable the C native extension invalidates this test"
     skip_on :no_bundler
     conf = Puma::Configuration.new do |c|
       c.extra_runtime_dependencies ['rdoc']

test/test_pumactl.rb

@@ -149,6 +149,7 @@ def test_control_url_and_status
   end
 
   def test_control_ssl
+    skip_on :jruby # ported from https://github.com/puma/puma/blob/4ef001000e71f987ccfacd28c3cbda614d3717ff/test/test_pumactl.rb#L144
     host = "127.0.0.1"
     port = find_open_port
     url = "ssl://#{host}:#{port}?#{ssl_query}"