Respect the -tail-dup-size command line option even when optimizing for size.

Respect the -tail-dup-size command line option even when optimizing for size.

This is similar to the -unroll-threshold option. There should be no change in
behavior when -tail-dup-size is not explicit on the llc command line.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124564 91177308-0d34-0410-b5e6-96231b3b80d8