Remove unnecessary typedef from std::function

	* include/bits/std_function.h (function::_Signature_type): Remove.
	(function::function(_Functor)): Adjust.

From-SVN: r244107

libstdc++-v3/ChangeLog

+2017-01-05  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/bits/std_function.h (function::_Signature_type): Remove.
+	(function::function(_Functor)): Adjust.
+
 2017-01-05  Tim Shen  <timshen@google.com>
 
 	PR libstdc++/78996

libstdc++-v3/include/bits/std_function.h

@@ -456,8 +456,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : public _Maybe_unary_or_binary_function<_Res, _ArgTypes...>,
       private _Function_base
     {
-      typedef _Res _Signature_type(_ArgTypes...);
-
       template<typename _Func,
 	       typename _Res2 = typename result_of<_Func&(_ArgTypes...)>::type>
 	struct _Callable : __check_func_return_type<_Res2, _Res> { };
@@ -715,7 +713,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       function(_Functor __f)
       : _Function_base()
       {
-	typedef _Function_handler<_Signature_type, _Functor> _My_handler;
+	typedef _Function_handler<_Res(_ArgTypes...), _Functor> _My_handler;
 
 	if (_My_handler::_M_not_empty_function(__f))
 	  {