Add test-powerpc to CI

[ianfixes]

With the example results file from #102, the test file SheepShaver/src/kpx_cpu/src/test/test-powerpc.cpp can somehow be leveraged to conduct automated tests.

It's unclear how this test should be built and executed, beyond the observations that:

1. the ppc-testresults.dat file (MD5 3e29432abb6e21e625a2eef8cf2f0840) should be stored in compressed form as ppc-testresults.dat.bz2 (MD5 60172863f951c72e1ee7e01d54ed6db3) -- 36MB vs 4.6MB
2. the test file seems to want to be provided as an input argument to the test program
3. the test file is handled differently depending on architecture (and I haven't dug into it further)

[ianfixes]

@asvitkine I saw your username on the directory with the test file, any insight you can offer will go directly into a README