Increase read_timeout for --jit-wait

This tries to fix a random failure like
http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/3017837

Author: k0kubun

test/net/http/test_httpresponse.rb

@@ -88,6 +88,7 @@ def test_read_body_block_mod
         :ok
       end
       io = Net::BufferedIO.new(r)
+      io.read_timeout *= 5 if RubyVM::MJIT.enabled? # for --jit-wait
       res = Net::HTTPResponse.read_new(io)
       nr = 0
       res.reading_body io, true do