Clang: Fix highlighting of primitive types

libClang categorizes these as keywords, so we need to check
if a keyword is actually a primitive type, and use that.

Task-number: QTCREATORBUG-17867
Change-Id: I354bb0422505ed7732a0799d9c86d3acfdeb0785
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/clangcodemodel/clanghighlightingmarksreporter.cpp

@@ -44,6 +44,8 @@ TextEditor::TextStyle toTextStyle(ClangBackEnd::HighlightingType type)
             return TextEditor::C_VIRTUAL_METHOD;
         case HighlightingType::Type:
             return TextEditor::C_TYPE;
+        case HighlightingType::PrimitiveType:
+            return TextEditor::C_PRIMITIVE_TYPE;
         case HighlightingType::LocalVariable:
             return TextEditor::C_LOCAL;
         case HighlightingType::Field: