Separate Compilation Tests

[kavon]

Should at least test the following situations

1. Standard separate compilation with -fhalo enabled for the object files / static libs and during linking to create the executable. It would be great if clang merges the bitcode in those object files into one module in the final executable.

2. A shared library compiled with -fhalo and an executable (also -fhalo) that uses it. In theory we should be able to access the bitcode in that module (by getting the patch from the proc map and loading the object file) to perform cross-library optimization.

3. A test case to cause a name clash during linking of two object files who originally did not export a certain global with identical names, but because of HaloPrepare's naive globalization of those symbols, breaks linking. This would motivate work on creating new aliases for these globals during HaloPrepare.

These would make great regression tests.