[ObjC][ARC] Don't remove autoreleaseRV/retainRV pairs if the call isn't

a tail call

This reapplies the patch in https://reviews.llvm.org/rG1f5b471b8bf4,
which was reverted because it was causing crashes.

https://bugs.chromium.org/p/chromium/issues/detail?id=1061289#c2

Check that HasSafePathToCall is true before checking the call is a tail
call.

Original commit message:

Previosly ARC optimizer removed the autoreleaseRV/retainRV pair in the
following code, which caused the object returned by @something to be
placed in the autorelease pool because the call to @something isn't a
tail call:

```
  %call = call i8* @something(...)
  %2 = call i8* @objc_retainAutoreleasedReturnValue(i8* %call)
  %3 = call i8* @objc_autoreleaseReturnValue(i8* %2)
  ret i8* %3
```

Fix the bug by checking whether @something is a tail call.

rdar://problem/59275894