Clarify comments.

llvm-svn: 186297
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 5a85047..deb2e60 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -311,10 +311,7 @@
   // All DIEValues are allocated through this allocator.
   BumpPtrAllocator DIEValueAllocator;
 
-  //===--------------------------------------------------------------------===//
-  // Attribute used to construct specific Dwarf sections.
-  //
-
+  // Handle to the a compile unit used for the inline extension handling.
   CompileUnit *FirstCU;
 
   // Maps MDNode with its corresponding CompileUnit.