This is the second part of a multi-part change to define additional
subcommands to the llvm-xray tool.
This change defines a conversion subcommand to take XRay log files, and
turns them from one format to another (binary or YAML). This currently
only supports the first version of the log file format, defined in the
compiler-rt runtime.
Depends on D21987.
This should be implicit? Or did you want it to disable the other special members? Any particular reason? (might be worth a comment if that's the case)