Workaround llvm::outs closing the stdout file descriptor.
Use NDEBUG when building the InstructionBitcode.bc file.
Add multithreaded dhrystone benchmark.
Add override keyword, remove some virtual destructors.
Use target_* commands to add includes / defines to the axe target.

Any targets that link against the axe library will automatically pick up
the right defines / includes. These commands require cmake 2.8.11 or later.