Until r216870 LLVMCreateObjectFile returned nullptr in case of an error,
so callers could check if the call was successful. Now, it always
returns an OwningBinary wrapped as an LLVMObjectFileRef, so callers
can't check if the call was successul.
This results in a segfault running e.g.
llvm-c-test --object-list-sections < /dev/null
So the old behaviour should be restored.