[FunctionAttrs] Annotate "willreturn" for AssumeLikeInst

Summary:
In D37215, AssumeLikeInstruction are regarded as `willreturn`. In this patch, annotation is added to those which don't have `willreturn` now(`sideeffect, object_size, experimental_widenable_condition`).

Reviewers: jdoerfert, nikic, sstefan1

Reviewed By: nikic

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65455

llvm-svn: 367342