[PM] Schedule InstSimplify after late LICM run, to clean up LCSSA nodes.

Summary:
The module pass pipeline includes a late LICM run after loop
unrolling.  LCSSA is implicitly run as a pass dependency of LICM.  However no
cleanup pass was run after this, so the LCSSA nodes ended in the optimized output.

Reviewers: hfinkel, mehdi_amini

Subscribers: majnemer, bruno, mzolotukhin, mehdi_amini, llvm-commits

Differential Revision: http://reviews.llvm.org/D20606

llvm-svn: 271602