* host builder nonregular files
* disallow links outside root
* add back in correct path support for windows
* code review updates
* host builder file test
* windows-specific absolute link check
* windows-specific test
* refactor
Resolve the link target one level higher such that it can be used
when creating the tar header without repetition.
* validate link header targets
* expand link test
* merge os-specific test cases
* remove os filter and unused arg
Plumbs through the platform CLI flag to the individual builders by
creating a client-level BuildOption functional option, and modifying the
builder interface to accept an optional set of requested target
platforms.