[llvm] [MachineOutliner] Preserve regmasks in calls to outlined functions (PR #120940)

[Zhaoxuan Jiang via llvm-commits]

nocchijiang wrote:

Having been occupied with the CNY and other company-related matters, I have finally had the opportunity to work on this PR. Given that @MatzeB has not provided any further comments, I presume you have been familiar with the context. I have addressed all comments from the participating reviewers in the latest commit.

https://github.com/llvm/llvm-project/pull/120940