Precommit AArch64 test for -consider-local-interval-cost

Summary:
Precommitting this test makes it more obvious what the delta is of enabling
-consider-local-interval-cost in D69437.

Reviewers: dmgreen

Subscribers: kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69512

Author: snnw