[2.1] Return in a lambda always returns from the block, even when &-ified

Update block jump handling to always locally return for lambdas, even if the lambda is &-ified (https://bugs.ruby-lang.org/issues/8693)

Fixes #1273.

(Travis is a bit stormy right now, but I was able to mostly sanity check this [here](https://travis-ci.org/dmarcotte/jruby/builds/17654784))