Remove the squishing of whitespace in header values

While the stripping of header values is required by RFC 2616 4.2 and
RFC 7230 3.2.4, the squishing is not and can break things, such as
when one header contains an HMAC of another header.

Fixes Ruby Bug 7021.

Author: jeremyevans

lib/webrick/httputils.rb

@@ -162,10 +162,7 @@ def parse_header(raw)
         end
       }
       header.each{|key, values|
-        values.each{|value|
-          value.strip!
-          value.gsub!(/\s+/, " ")
-        }
+        values.each(&:strip!)
       }
       header
     end

test/webrick/test_httprequest.rb

@@ -135,7 +135,7 @@ def test_parse_header2()
     assert_equal("", req.script_name)
     assert_equal("/foo/baz", req.path_info)
     assert_equal("9", req['content-length'])
-    assert_equal("FOO BAR BAZ", req['user-agent'])
+    assert_equal("FOO   BAR BAZ", req['user-agent'])
     assert_equal("hogehoge\n", req.body)
   end