[Attributor] Introduce checkForAllReadWriteInstructions(...).

Summary: Similarly to D65731 `Attributor::checkForAllReadWriteInstructions` is introduced.

Reviewers: jdoerfert, uenoku

Subscribers: hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65825

llvm-svn: 368194