Remove NoVendor and NoOS, added in commit 123990, from Triple. While it

may be useful to understand "none", this is not the place for it.  Tweak
the fix to Normalize while there: the fix added in 123990 works correctly,
but I like this way better.  Finally, now that Triple understands some
non-trivial environment values, teach the unittests about them.

llvm-svn: 124720