MC: Extend MCAsmLayout to explicitly track which fragments have been layed out, and enforce several invariants to LayoutFragment to ensure we only do layout in a sensible order.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103753 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed