[DebugInfo] Prep llvm-dwarfdump for typed DW5 ops.

Adds llvm-dwarfdump support for pretty printing Dwarf5 expressions ops
that reference a base type (right now only DW_OP_convert is added).
Includes verification to verify that the ops operand is actually a
DW_TAG_base_type DIE.

Differential Revision: https://reviews.llvm.org/D58442

llvm-svn: 354552
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
index 154e466..c112d2b 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
@@ -266,7 +266,7 @@
   case OT_Expression:
     assert(Instr.Expression && "missing DWARFExpression object");
     OS << " ";
-    Instr.Expression->print(OS, MRI, IsEH);
+    Instr.Expression->print(OS, MRI, nullptr, IsEH);
     break;
   }
 }