Old run_tests.sh still lives (for now).
Changes include:
- Tests are run in parallel across all of the available CPU cores
- Option to create a statically-linked executable for each test
(rather than using the LLVM JIT). This is in particular useful
for AVX, which doesn't have good JIT support yet.
- Static executables also makes it possible to test x86, not
just x86-64, codegen.
- Fixed a number of tests in failing_tests, which were actually
failing due to the fact that the expected function signature of
tests had changed.
