CodeGen: Push the ModuleSlotTracker through MachineOperands

Push `ModuleSlotTracker` through `MachineOperand`s, dropping the time
for `llc -print-machineinstrs` on the testcase in PR23865 from ~13
seconds to ~9 seconds.  Now `SlotTracker::processFunctionMetadata()`
accounts for only 8% of the runtime, which seems reasonable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240845 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed