Test output:

```
[ RUN ] codestrings.validate_vm
/sapmnt/sapjvm_work/openjdk/nb/linuxppc64le/jdk-dev/test/hotspot/gtest/code/test_codestrings.cpp:179: Failure
Value of: cbuf.dbg_strings().is_empty()
  Actual: true
Expected: false
/sapmnt/sapjvm_work/openjdk/nb/linuxppc64le/jdk-dev/test/hotspot/gtest/code/test_codestrings.cpp:249: Failure
Value of: cbuf.dbg_strings().is_empty()
  Actual: true
Expected: false
[ FAILED ] codestrings.validate_vm (2 ms)
```

Problem is that the tests assumes that `MacroAssembler::unimplemented()` uses code strings, which it does not on ppc64 (s390 too AFAICT).