@larskanis is this needed? Bump to 0.9.1 is probably enough.

I'm getting with this:

```
cp Rakefile build/i386-mingw32/stage/Rakefile
install -c build/i386-mingw32/ffi_c/1.8.7/ffi_c.so lib/1.8/ffi_c.so
cp build/i386-mingw32/ffi_c/1.8.7/ffi_c.so build/i386-mingw32/stage/lib/1.8/ffi_c.so
i686-w64-mingw32-strip -S build/i386-mingw32/stage/lib/1.8/ffi_c.so
i686-w64-mingw32-strip:build/i386-mingw32/stage/lib/1.8/stpiC9mH: Protocol error
rake aborted!
Command failed with status (1): [i686-w64-mingw32-strip -S build/i386-mingw...]
/vagrant/ffi/Rakefile:208
/home/vagrant/.rvm/gems/ruby-1.8.7-p374/bin/ruby_executable_hooks:15
Tasks: TOP => native => native:i386-mingw32 => native:ffi:i386-mingw32 => build/i386-mingw32/stage/lib/1.8/ffi_c.so => copy:ffi_c:i386-mingw32:1.8.7
(See full trace by running task with --trace)
```

Without this block I'm getting stripped binaries (except 1.9).