Run automatic deflate decoding only if it has zlib.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36678 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/net/http/test_httpresponse.rb

@@ -93,7 +93,7 @@ EOS
     end
 
     assert_equal 'hello', body
-  end
+  end if Net::HTTP::HAVE_ZLIB
 
   def test_read_body_content_encoding_deflate_chunked
     io = dummy_io(<<EOS)
@@ -119,7 +119,7 @@ EOS
     end
 
     assert_equal 'hello', body
-  end
+  end if Net::HTTP::HAVE_ZLIB
 
   def test_read_body_content_encoding_deflate_no_length
     io = dummy_io(<<EOS)
@@ -139,7 +139,7 @@ EOS
     end
 
     assert_equal 'hello', body
-  end
+  end if Net::HTTP::HAVE_ZLIB
 
   def test_read_body_content_encoding_deflate_content_range
     io = dummy_io(<<EOS)