RuntimeError with compiled multi-byte variable

multibytevar.rb
```
# coding: utf-8

# 'α'.bytes => [206, 177]
p α = 1
```
run with jruby 9.1.9.0
```
$ jruby multibytevar.rb
1
```
compile and run with jruby 9.1.9.0
```
$ jrubyc multibytevar.rb
$ jruby multibytevar.class
RuntimeError: BUG: interpreter fell through to end unexpectedly
  <main> at multibytevar.class:1
```
