Revert "Inliner: Handle readonly attribute per argument when adding memcpy"

This reverts commit r193356, it caused PR17781.

A reduced test case covering this regression has been added to the test suite.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193955 91177308-0d34-0410-b5e6-96231b3b80d8