We removed the ability to automatically load extensions from jars
many years ago, but this test remained. It only continued to pass
because some other library loaded the 'json' library which meant
that the tested classes were available. When this same example is
run outside of the test suite, it fails:

```
$ cx jruby-10.0.2.0 ruby -e "require 'uri:file:./lib/ruby/stdlib/json/ext/parser'; p JSON::Ext::Parser"
NameError: uninitialized constant JSON::Ext::Parser
  const_missing at org/jruby/RubyModule.java:4866
         <main> at -e:1
```

Because this functionality no longer exists, I am removing the
test.

A few additional stdlib were added in 4.0 so this archive is now
a bit larger.

* Removed SortedSet and related files (gem TBD).
* Removed stdlib .rb stub.
* Fixed inspect output, intersect? with Array, and infinite
  enumerables for new tests.
* Moved @hash variable to a bound Java field.

* Fix inspect output expectations.
* Guard SortedSet tests behind a require, since that collection is
  now in a separate library (knu/sorted_set). These tests probably
  should move to the external library once we work out the details
  (see knu/sorted_set#7)

Based on code from CRuby by Tomoya Ishida:

ruby/ruby#13680

When the incoming block's signature is important to the iteration
method being called, the previous logic would hide that signature.
The change here propagates it through the CallBlock.

This does not exactly match the new native Set impl, but it passes
specs and tests related to initialize.

This updates some logic related to the new native Set.

Only fails are now related to us not tracking iteration-in-progress
for either Set or Hash.

Properly handle keywords in {Kernel|Thread|Fiber}#raise

For unescape when the source has characters that can't be
represented in the target encoding, use the source encoding for the
destination string.

Remove "infectBy" call from tainting days.

See #8714

See #8660

See #9250

This aliasing and unaliasing of methods to temporarily remove them
does not appear to work properly in JRuby. Im excluding the tests
since this is a very peculiar scenario users probably will never
run into, and excluding the hacky tests allows the others to all
pass.

See #9251

See #8660

See #8714

See #9250

No changes other than jcodings 1.0.64.

Set no longer aggregates a Hash in CRuby. Ours does for now, but
don't expose it anymore.

JRuby never loads extensions as .so and pathname is provided as a
pathname.rb.