Unnecesary template member in communicator

[RaulPPelaez]

mpl/mpl/comm_group.hpp

Lines 895 to 904 in 3012645

	template<typename T>
	std::pair<bool, status> iprobe(int source, tag t=tag(0)) const {
	check_source(source);
	check_recv_tag(t);
	int result;
	status s;
	MPI_Iprobe(source, static_cast<int>(t),
	comm, &result, reinterpret_cast<MPI_Status *>(&s));
	return std::make_pair(static_cast<bool>(result), s);
	}

The iprobe member is declared as a template but the template argument is never used, it is necessary to explicitly provide an argument for this member to compile, even when the argument itself is irrelevant.
This means this simple line wont compile (at least with my OpenMPI-4.0.0 + g++-5.5):

#include<mpl/mpl.hpp>
int main(){
   mpl::environment::comm_world().iprobe(mpl::any_source); 
return 0;
}

Unless you put <literally any typename> after iprobe.
Just commenting line 895 above solves the issue.