Make \r optional in chunk size detection

As pointed out by Ken Ballus, WEBrick allows \n without preceding
\r generally.  It probably shouldn't, but since it does, do not
require \r for chunk size detection.

Author: jeremyevans

lib/webrick/httprequest.rb

@@ -542,7 +542,7 @@ def read_body(socket, block)
 
     def read_chunk_size(socket)
       line = read_line(socket)
-      if /\A([0-9a-fA-F]+)(?:;(\S+(?:=\S+)?))?\r\n\z/ =~ line
+      if /\A([0-9a-fA-F]+)(?:;(\S+(?:=\S+)?))?\r?\n\z/ =~ line
         chunk_size = $1.hex
         chunk_ext = $2
         [ chunk_size, chunk_ext ]