[CodeGen/AccelTable]: Handle -dwarf-linkage-names=Abstract correctly

Summary:
If we are not emitting a linkage name in the .debug_info sections, we
should not add it into the index either. This makes sure our index is
consistent with the actual debug info.

I am also explicitly setting the --dwarf-linkage-names=All in the
name-collsions test as that one would now fail on targets where this
defaults to "Abstract" (in fact, it would have failed already if there
wasn't a bug in the DWARF verifier, which I fix as well).

Reviewers: probinson, aprantl, JDevlieghere

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D46748

llvm-svn: 332246
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp b/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
index ba7aef37..b3b8d7d 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
@@ -1122,6 +1122,7 @@
                          "of DIE @ {2:x}: index - {3}; debug_info - {4}.\n",
                          NI.getUnitOffset(), EntryID, DIEOffset, Str,
                          make_range(EntryNames.begin(), EntryNames.end()));
+      ++NumErrors;
     }
   }
   handleAllErrors(EntryOr.takeError(),