Hipe test fix

I found out that the HiPE tests were not properly included in the generated Emakefile, most probably due to the fact that there was no such command before the change that checks the consistency of the hipe.app file. Anyway, now they should be and the test suite should now include running the bs_SUITE.

While at it, also modified the test suite driver to also test the correctness of the new LLVM backend if the test machine has proper infrastructure for the LLVM compiler.