Pass CFLAGS to clang invocations in tests.
Add 'soaap' script.

Instead of 'opt -load libsoaap.so -soaap' (which might actually use libsoaap.dylib on OS X), provide a 'soaap' script that does these things for us.

Use this script in tests.
cep_rt must link against libprofile_rt.

Some linkers will let you create a shared library without knowing if an external symbol exists in another library, but not all.

We can now build SOAAP on Mac OS X!
Try Harder to find LLVM opt.

If it's not in the PATH, look in LLVM_BINARY_DIR.