RFR(S): 8187670: [MVT] Enable verifier for compiler tests

[Tobias Hartmann]

Hi,

please review the following change that enables the verifier for the compiler tests by fixing some minor issues:
https://bugs.openjdk.java.net/browse/JDK-8187670
http://cr.openjdk.java.net/~thartmann/8187670/webrev.00/

All tests pass.

Thanks,
Tobias