DwarfDebug: Avoid an extra map lookup while constructing abstract scope DIEs and reduce nesting/conditionals.

One test case had to be updated as it still had the extra indirection
for the variable list - removing the extra indirection got it back to
passing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208608 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed