stdlib: use IO#wait_*able instead of IO.select when possible

In case a process encounters high-numbered FDs, this allows
consistent performance on systems with ppoll support.
[ruby-core:35572]

* ext/socket/lib/socket.rb (connect_nonblock): use IO#wait_writable
* lib/drb/drb.rb (DRB::DRbTCPSocket#alive?): use IO#wait_readable
* lib/webrick/httpserver.rb (run): ditto
* lib/resolv.rb (request): ditto for single socket case
  [ruby-core:68943] [Feature #11081]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50432 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/webrick/httpserver.rb

@@ -8,6 +8,7 @@
 #
 # $IPR: httpserver.rb,v 1.63 2002/10/01 17:16:32 gotoyuzo Exp $
 
+require 'io/wait'
 require 'webrick/server'
 require 'webrick/httputils'
 require 'webrick/httpstatus'
@@ -72,7 +73,7 @@ module WEBrick
         begin
           timeout = @config[:RequestTimeout]
           while timeout > 0
-            break if IO.select([sock], nil, nil, 0.5)
+            break if sock.to_io.wait_readable(0.5)
             break if @status != :Running
             timeout -= 0.5
           end