Patch from Andrew Kaylor that centralized where the info for:

ConstString Host::GetVendorString();
ConstString Host::GetOSString();

comes from. It now all comes from the Host::GetArchitecture (eSystemDefaultArchitecture) like the Apple build was doing to minimize the number of places that need to be updated when Host::GetArchitecture () is called.

llvm-svn: 165805