Simplifies the process of building an LLJIT instance that supports the native
platform features (initializers, TLV, etc.).
SetUpExecutorNativePlatform can be passed to LLJITBuilder::setPlatformSetUp
method. It takes a reference to the ORC runtime (as a path or an in-memory
archive) and automatically sets the platform for LLJIT's ExecutionSession based
on the executor process's triple.
This is a rough draft -- we'll need more polish and some tests before this
lands. In particular we need to re-work ORCPlatformSupport to handle
COFF/Windows. We could take this opportunity to do away with the whole
LLJITPlatformSupport concept. It really only exists to implement initialize
and deinitialize, so I think that we could instead define standard functions
"orc_rt_lljit_initialize" and "orc_rt_lljit_deinitialize" and alias them
to platform-specific implementations (a wrapper for dlopen on *nix, a wrapper
for LoadLibrary for Windows, etc.).