clang-format: Revamp builder-type call formatting.

Previously builder-type calls were only correctly recognized in
top-level calls.

This fixes llvm.org/PR16981.
Before:
  someobj->Add((new util::filetools::Handler(dir))->OnEvent1(
      NewPermanentCallback(this, &HandlerHolderClass::EventHandlerCBA))
                   ->OnEvent2(NewPermanentCallback(
                                  this, &HandlerHolderClass::EventHandlerCBB))
                   ->OnEvent3(NewPermanentCallback(
                                  this, &HandlerHolderClass::EventHandlerCBC))
                   ->OnEvent5(NewPermanentCallback(
                                  this, &HandlerHolderClass::EventHandlerCBD))
                   ->OnEvent6(NewPermanentCallback(
                         this, &HandlerHolderClass::EventHandlerCBE)));

After:
  someobj->Add((new util::filetools::Handler(dir))
                   ->OnEvent1(NewPermanentCallback(
                         this, &HandlerHolderClass::EventHandlerCBA))
                   ->OnEvent2(NewPermanentCallback(
                         this, &HandlerHolderClass::EventHandlerCBB))
                   ->OnEvent3(NewPermanentCallback(
                         this, &HandlerHolderClass::EventHandlerCBC))
                   ->OnEvent5(NewPermanentCallback(
                         this, &HandlerHolderClass::EventHandlerCBD))
                   ->OnEvent6(NewPermanentCallback(
                         this, &HandlerHolderClass::EventHandlerCBE)));