Revert "[BuildLibCalls/SimplifyLibCalls] Fix attributes on created CallInst instructions."

This reverts commit 1eda5453.

Causes https://crbug.com/1223647:
Incompatible argument and return types for 'returned' attribute
  tail call void @llvm.memset.p0i8.i64(i8* noalias noundef returned writeonly align 1 dereferenceable(255) %arraydecay, i8 0, i64 255, i1 false), !dbg !985