serialized diagnostics: implement full deserialization of clang diagnostics via the libclang API.

I've tested it on simple cases and it works.  Test cases to follow as well as a few tweaks.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144269 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 0f93931..f9a8738 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -58,6 +58,7 @@
   CXTranslationUnit D = new CXTranslationUnitImpl();
   D->TUData = TU;
   D->StringPool = createCXStringPool();
+  D->Diagnostics = 0;
   return D;
 }
 
@@ -2562,6 +2563,7 @@
 
     delete static_cast<ASTUnit *>(CTUnit->TUData);
     disposeCXStringPool(CTUnit->StringPool);
+    delete static_cast<CXDiagnosticSetImpl *>(CTUnit->Diagnostics);
     delete CTUnit;
   }
 }
@@ -2582,6 +2584,11 @@
   ReparseTranslationUnitInfo *RTUI =
     static_cast<ReparseTranslationUnitInfo*>(UserData);
   CXTranslationUnit TU = RTUI->TU;
+
+  // Reset the associated diagnostics.
+  delete static_cast<CXDiagnosticSetImpl*>(TU->Diagnostics);
+  TU->Diagnostics = 0;
+
   unsigned num_unsaved_files = RTUI->num_unsaved_files;
   struct CXUnsavedFile *unsaved_files = RTUI->unsaved_files;
   unsigned options = RTUI->options;