Overhaul my earlier submission due to feedback. It's a large patch, but most of

Overhaul my earlier submission due to feedback. It's a large patch, but most of
them are generic changes.

- Use the "fast" flag that's already being passed into the asm printers instead
  of shoving it into the DwarfWriter.

- Instead of calling "MI->getParent()->getParent()" for every MI, set the
  machine function when calling "runOnMachineFunction" in the asm printers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65379 91177308-0d34-0410-b5e6-96231b3b80d8