When PlatformDarwinKernel::ExamineKextForMatchingUUID is given
a FileSpec, UUID, and ArchSpec, and it's opening all the kexts
with the same bundle id to see if they're a match, don't set
the Arch in the ModuleSpec.  If Module::GetObjectFile() sees
that the architecture of the kext is a mismatch for the arch
we're looking for, it'll spew a warning message to the dev (r217251).

Rely on the UUID match to get the correct file if we have
a UUID -- we'll get no warning if it's a mismatch.

<rdar://problem/18641477>