instcombine: Migrate puts optimizations

This patch migrates the puts optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

All the simplifiers from simplify-libcalls have now been migrated to
instcombine.  Yay!  Just a few other bits to migrate (prototype attribute
inference and a few statistics) and simplify-libcalls can finally be put
to rest.

llvm-svn: 168925