IfConversion: Use range based for; NFC

Also avoid some pointless use of auto! Because that's friendlier to
readers and avoids several types accidentally resolving to unnecessary
references here (MachineInstr *&, unsigned &).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278894 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed