Extended Description

Allocation actions are run during JIT memory finalization and deallocation. The code for these actions may be in the ORC runtime. This makes them an awkward fit for llvm-jitlink -noexec tests, which (1) are meant to be able to run on all platforms, including platforms that can't execute the code being jit-linked at all (e.g. arm64 tests running on an x86-64 tester), and (2) ideally shouldn't assume that we have a built ORC runtime.

We could solve this by:
(1) Adding a jitlink-test-environment dylib to the build that provides mocks of the required actions.
(2) Add a new "add-executor-mangled-alias " option to llvm-jitlink which adds aliases of the form executor_mangle() -> Dylib::lookup() to the session.

This will cause allocation actions to be redirected to code executable on the host and we can use this to print debugging output that can be used to verify that the required actions were run.