Start the refactoring of globbing

- Add Host::GlobArguments() to perform local-globbing
I implemented this on OSX and Windows in terms of argdumper (Windows implementation is essentially the same as the OSX version + a change in binary name and some string magic)
Other platforms did not specifically chime in, so I left it unimplemented for them for the time being. Please feel free to fill in the blanks

- Add Platform::GlobArguments() to support remote-globbing
For now, no feature change here - but now we have infrastructure to help GDBRemote targets to support globbing - and patches to that effect will follow

No visible feature change

llvm-svn: 230065