Only split around a loop if the live range has uses outside the loop periphery.

Only split around a loop if the live range has uses outside the loop periphery.

Before we would also split around a loop if any peripheral block had multiple
uses. This could cause repeated splitting when splitting a different live range
would insert uses into the periphery.

Now -spiller=inline passes the nightly test suite again.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116494 91177308-0d34-0410-b5e6-96231b3b80d8