[libclang] Fix a warning

This patch fixes:

  clang/tools/libclang/CXIndexDataConsumer.cpp:1235:11: error:
  enumeration value 'IncludeDirective' not handled in switch
  [-Werror,-Wswitch]

Author: kazutakahirata

clang/tools/libclang/CXIndexDataConsumer.cpp

@@ -1241,6 +1241,7 @@ static CXIdxEntityKind getEntityKindFromSymbolKind(SymbolKind K, SymbolLanguage
   case SymbolKind::TemplateTypeParm:
   case SymbolKind::TemplateTemplateParm:
   case SymbolKind::NonTypeTemplateParm:
+  case SymbolKind::IncludeDirective:
     return CXIdxEntity_Unexposed;
 
   case SymbolKind::Enum: return CXIdxEntity_Enum;