DebugInfo: Fix and test a regression caused by r207263 causing the DW_AT_object_pointer to go missing on blocks

Noticed by inspection. Test coverage added.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207333 91177308-0d34-0410-b5e6-96231b3b80d8
DwarfDebug: Roll argument into call.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207334 91177308-0d34-0410-b5e6-96231b3b80d8
[LCG] Switch the node iterator to use the new fancy adaptor base. This
is *much* cleaner, makes the iterator a full random access iterator,
etc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207335 91177308-0d34-0410-b5e6-96231b3b80d8
[LCG] Eliminate more boiler plate by using the iterator facade base
class.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207336 91177308-0d34-0410-b5e6-96231b3b80d8