Debug Info: add support to mark member variables as artificial

This is the LLVM portion of r170154.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170156 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -1559,6 +1559,9 @@ DIE *CompileUnit::createMemberDIE(DIDerivedType DT) {
       MemberDie->addValue(dwarf::DW_AT_APPLE_property, dwarf::DW_FORM_ref4,
                           PropertyDie);
 
+  if (DT.isArtificial())
+    addFlag(MemberDie, dwarf::DW_AT_artificial);
+
   // This is only for backward compatibility.
   StringRef PropertyName = DT.getObjCPropertyName();
   if (!PropertyName.empty()) {