Stabilize the order of live intervals in the priority_queue used by the

Stabilize the order of live intervals in the priority_queue used by the
linear scan reg alloc.  This fixes a problem I ran into where extracting
a function from a larger file caused the generated code to change (masking
the problem I was trying to debug) because the allocator behaved differently.

This changes the results for two X86 regression checks.  stack-color-with-reg
is improved, with one less instruction, but pr3495 is worse, with one more
copy.  As far as I can tell, these tests were just getting lucky or unlucky,
so I've changed the expected results.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81060 91177308-0d34-0410-b5e6-96231b3b80d8