[Downstream Change] [ATfE 21] Forward -Os and -Oz as multilib flags #528
Description
What is the change
Pass along -Os and -Oz as multilib flags under ARM and AArch64 so that they can be used as criteria for multilib selection.
This is a cherry-pick of 579a807 onto our 21 branch, so it falls under the "Backports critical to Arm for a numbered release" category.
Why this change cannot be done upstream
This commit was merged in upstream LLVM after the branching for 21 had been made. The patch is not a bug fix and is very specific to the interests of ATfE, therefore I don't see this commit being accepted for a backport.