[test] 40chunked.t: convert the length of the chunk from hexadecimal
[test] 40chunked.t: convert the length of the chunk from hexadecimal

this might explain https://github.com/h2o/h2o/issues/2028: most of the
time we should see a number between 1 and 2, but timing issues might
result in a larger hex number, causing the test to fail

h2o/h2o,devnexen/h2o,cwyang/h2o,deweerdt/h2o,yannick/h2o,h2o/h2o,devnexen/h2o,devnexen/h2o,yannick/h2o,cwyang/h2o,cwyang/h2o,h2o/h2o,devnexen/h2o,deweerdt/h2o,cwyang/h2o,yannick/h2o,cwyang/h2o,deweerdt/h2o,devnexen/h2o,yannick/h2o,devnexen/h2o,devnexen/h2o,cwyang/h2o,deweerdt/h2o,cwyang/h2o,h2o/h2o,cwyang/h2o,yannick/h2o,deweerdt/h2o,h2o/h2o,h2o/h2o,h2o/h2o,deweerdt/h2o,h2o/h2o,yannick/h2o,devnexen/h2o,h2o/h2o,deweerdt/h2o,yannick/h2o,deweerdt/h2o,yannick/h2o,deweerdt/h2o,devnexen/h2o,yannick/h2o