Followup to r309570, fixing it slightly differently (ranges_base and
addr_base should never be read from a DWO file - so there shouldn't be
any issue with 'overriding' the values - conditionalize the code and
assert that the values aren't being overriden).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@309879 91177308-0d34-0410-b5e6-96231b3b80d8