Make std::bind use std::invoke
* include/std/functional (_Mu<A, false, true>, _Mu<A, true, false>):
Simplify forwarding from tuple of references.
(_Maybe_wrap_member_pointer): Remove.
(_Bind::__call, _Bind::__call_c, _Bind::__call_v, _Bind::__call_c_v):
Use std::__invoke.
(_Bind::_Mu_type, _Bind::_Res_type_impl, _Bind::_Res_type)
(_Bind::__dependent, _Bind::_Res_type_cv): New helpers to simplify
return type deduction.
(_Bind::operator(), _Bind::operator() const): Use new helpers.
(_Bind::operator() volatile, _Bind::operator() const volatile):
Likewise. Add deprecated attribute for C++17 mode.
(_Bind_result::__call): Use std::__invoke.
(_Bind_result::operator() volatile)
(_Bind_result::operator() const volatile): Add deprecated attribute.
(_Bind_helper::__maybe_type, _Bindres_helper::__maybe_type): Remove.
(_Bind_helper, _Bindres_helper): Don't use _Maybe_wrap_member_pointer.
(bind, bind<R>): Don't use __maybe_type.
* src/c++11/compatibility-thread-c++0x.cc
(_Maybe_wrap_member_pointer): Define here for compatibility symbols.
* testsuite/20_util/bind/68912.cc: Don't test volatile-qualification
in C++17 mode.
* testsuite/20_util/bind/cv_quals.cc: Likewise.
* testsuite/20_util/bind/cv_quals_2.cc: Likewise.
From-SVN: r241178
de1d079440