[CodeGen] Print live-out register lists as liveout(...) in both MIR and debug output

Work towards the unification of MIR and debug output by printing
`liveout(...)` instead of `<regliveout>`.

Only debug syntax is affected.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320683 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed