ASMParser: use range-based for loops (NFC)

Convert the verify method to use a few more range based for loops,
converting to const iterators in the process.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290617 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed