Wordsmith and simplify

Simplify expressions as suggested by jhb. The extra indirection made
sense in earlier versions of this patch, but not the final one.

While here, apply suggestion from emaste for wording of universe.
Also wordsmith awkwardly worded comment about when we effectively
neuter the universe build for an architecture.

Once llvm 9.0 has been vetted for mips and powerpc, I'll take them out
of these lists.