Hack more exceptions to ignore

There are concurrent shutdown issues with WEBrick that have never
been fixed (ruby/webrick#102 which may explain why we get these
sporadic failures in several of the net/http tests:

```
  1) Error:
TestNetHTTP_v1_2#test_s_start:
Errno::EPIPE: Broken pipe - No message available
    org/jruby/RubyIO.java:1391:in `write_nonblock'
    /home/runner/work/jruby/jruby/test/tool/lib/webrick/server.rb:227:in `block in stop'
    /home/runner/work/jruby/jruby/test/tool/lib/webrick/server.rb:352:in `alarm_shutdown_pipe'
    /home/runner/work/jruby/jruby/test/tool/lib/webrick/server.rb:227:in `stop'
    /home/runner/work/jruby/jruby/test/tool/lib/webrick/server.rb:235:in `shutdown'
    /home/runner/work/jruby/jruby/test/mri/net/http/utils.rb:37:in `teardown'
```

I have commented on the issue and this commit adds more exceptions
to ignore in an attempt to prevent unsafe shutdown from causing
any tests to fail.

Author: headius

Diff for: test/tool/lib/webrick/server.rb

@@ -350,7 +350,7 @@ def alarm_shutdown_pipe
         if !pipe.closed?
           begin
             yield pipe
-          rescue IOError # closed by another thread.
+          rescue IOError, Errno::EBADF, Errno::EPIPE # closed by another thread.
           end
         end
       end