R600: Rewrite an awkward loop in R600MachineScheduler

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183458 91177308-0d34-0410-b5e6-96231b3b80d8
CodeGenSchedule: smallvector.push_back(smallvector[0]) is dangerous

The element passed to push_back is not copied before the vector reallocates.
The client needs to copy the element first before passing it to push_back.

No test case, will be tested by follow-up swift scheduler model change (it
segfaults without this change).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183459 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unneeded #include.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183460 91177308-0d34-0410-b5e6-96231b3b80d8
Simplify code. No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183461 91177308-0d34-0410-b5e6-96231b3b80d8