[Carpetsmoker]

/// Target triples are strings in the canonical form:
///   ARCHITECTURE-VENDOR-OPERATING_SYSTEM
/// or
///   ARCHITECTURE-VENDOR-OPERATING_SYSTEM-ENVIRONMENT

In this case the vendor is `unknown'.

Possible vendors seem to be:

  enum VendorType {
    UnknownVendor,

    Apple,
    PC,
    SCEI
  };

(See: src/contrib/llvm/tools/clang/lib/Driver/Driver.cpp and src/contrib/llvm/include/llvm/ADT/Triple.h)

AFAIK this does nothing or very little, but I didn't investigate further.