Support for DWARF-5 C++ language tags.

This patch provides support for DW_LANG_C_plus_plus_11,
DW_LANG_C_plus_plus_14 tags in the Clang C++ frontend.

Patch by Sourabh Singh Tomar!
Differential Revision: https://reviews.llvm.org/D67613

Reapplies r372663 after adapting a failing test in the LLDB testsuite.

llvm-svn: 372681
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index e656fe6..220ffb8 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -561,6 +561,10 @@
   if (LO.CPlusPlus) {
     if (LO.ObjC)
       LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
+    else if (LO.CPlusPlus14)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus_14;
+    else if (LO.CPlusPlus11)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus_11;
     else
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
   } else if (LO.ObjC) {
@@ -878,6 +882,8 @@
 static bool hasCXXMangling(const TagDecl *TD, llvm::DICompileUnit *TheCU) {
   switch (TheCU->getSourceLanguage()) {
   case llvm::dwarf::DW_LANG_C_plus_plus:
+  case llvm::dwarf::DW_LANG_C_plus_plus_11:
+  case llvm::dwarf::DW_LANG_C_plus_plus_14:
     return true;
   case llvm::dwarf::DW_LANG_ObjC_plus_plus:
     return isa<CXXRecordDecl>(TD) || isa<EnumDecl>(TD);