Change the scheduler from adding nodes in allnodes order

Change the scheduler from adding nodes in allnodes order
to adding them in a determinstic order (bottom up from
the root) based on the structure of the graph itself.

This updates tests for some random changes, interesting
bits: CodeGen/Blackfin/promote-logic.ll no longer crashes.
I have no idea why, but that's good right?

CodeGen/X86/2009-07-16-LoadFoldingBug.ll also fails, but
now compiles to have one fewer constant pool entry, making
the expected load that was being folded disappear.  Since it
is an unreduced mass of gnast, I just removed it.

This fixes PR6370

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97023 91177308-0d34-0410-b5e6-96231b3b80d8