Switch lowering: improve partitioning of jump tables

When there's a tie between partitionings of jump tables, consider also cases
that result in no jump tables, but in one or a few cases.  The motivation is
that many contemporary processors typically perform case switches fairly
quickly.

Differential revision: https://reviews.llvm.org/D25212

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@285099 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed