This is a follow-on to https://reviews.llvm.org/D49214, which received some additional review comments after closing.
Addresses the following:
- Fixing a bug with duplicate emission of DW_AT_rnglists_base with test case.
- Fixing a somewhat stale comment to constructSkeletonCU() and moving it to the header.
- Refactor DwarfDebug::emitDebugRanges() to handle both v5 and prior.
- Some minor grammatical tweaks.
Dave already handled the base address specifier issues mentioned in the other review, as well as some test coverage additions in a different revision. Thanks!