fix blocking function call spec in ffi
[Truffle] Use BigInteger#equals instead of compareTo when possible.
[Truffle] Implement Kernel#to_s for all objects and use it in ToSNode.

* Fix fallback to use Kernel#to_s on object, not its class.
* Use the lazy pattern for the kernelToSNode since it should be rarely used.
[Truffle] Prune language tags.

$ ruby spec/mspec/bin/mspec tag --purge --config spec/truffle/truffle.mspec spec/ruby/language -t /path/to/ruby-trunk
[Truffle] Very basic keyword arguments.
Merge pull request #2303 from tduehr/ffi_spec_change

fix blocking function call spec in ffi
Make sleep interrupts more robust by using Semaphore.
[Truffle] Partial implementation of Array#reject.
[Truffle] Untagged passing spec now that Array#reject works.