[LazyMachineBFI] Add testcase

This is based on Justin's testcase and checking whether BFI is not populated
in case hotness is off.

This is a patch meant on top of Justin's patch to enable Machine opt-remarks
in the
AsmPrinter (http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170130/426595.html)

Differential Revision: https://reviews.llvm.org/D29837

llvm-svn: 296065