mruby/mruby — pull request #606 by masamitsu-murase (2012-12-09 17:41:43+00:00)
Title: Fix memory leak in String#to_i and String#to_f.

String#to_i causes memory leak if the receiver is a shared string.

Use str_new instead of mrb_malloc so that GC can manage the buffer.

Error case:
```ruby
a = "0x10000 aaaaaaaaaaaaaaaaaaaaa".slice(0 .. 3)
100000000.times do
a.to_f
end
```