Otherwise we use the same threshold as for complete unrolling, which is
way too high. This made us unroll any loop smaller than 150 instructions
by 8 times, but only if someone specified -march=core2 or better,
which happens to be the default on darwin.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207940 91177308-0d34-0410-b5e6-96231b3b80d8