Since `raw_string_ostream` doesn't own the string buffer, it is
desirable (in terms of memory safety) for users to directly reference
the string buffer rather than use `raw_string_ostream::str()`.
Work towards TODO item to remove `raw_string_ostream::str()`.
* Capture reexported libraries, allowable clients, rpaths, shared cache
eligibility.
* Add support for select Xarch options.
* Add diagnostics related to capturing these options.
* Add support for verifying these attributes against what is encoded in
the dylib.