MachOUniversalBinary::getObjectForArch() returns a value containing
a unique_ptr; if we just fish out the unique_ptr value using get(),
it will be freed too soon.
Instead, hold on to the unique_ptr until we are done with everything.
swift-reflection-test is now the test that forks a swift executable
and performs remote reflection, making it runnable on other targets,
such as the iOS simulator.
swift-reflection-dump is now a host-side tool that dumps the remote
reflection sections for any platform binary and will continue to
link in LLVM object file support.
This necessitates finally moving lib/Refleciton into stdlib/public,
since we're linking target-specific versions of the test tool and
we would eventually like to adopt some of this functionality in
the runtime anyway.
