message: index stl declarations
diff: namespace {
  +const bool kIndexStdDeclarations = true;
  +
  void AddFuncRef(std::vector<IndexFuncRef>* result, IndexFuncRef ref) {
  if (!result->empty() && (*result)[result->size() - 1] == ref)
  return;
  @@ -710,7 +712,7 @@ bool AreEqualLocations(CXIdxLoc loc, CXCursor cursor) {
  void indexDeclaration(CXClientData client_data, const CXIdxDeclInfo* decl) {
  // TODO: allow user to configure if they want STL index.
  - if (clang_Location_isInSystemHeader(clang_indexLoc_getCXSourceLocation(decl->loc)))
  + if (!kIndexStdDeclarations && clang_Location_isInSystemHeader(clang_indexLoc_getCXSourceLocation(decl->loc)))
  return;
  assert(AreEqualLocations(decl->loc, decl->cursor));
  