Fix sample argument bug

fixes: a weight could pass as sample and vice versa

test/profile_fail3.cpp

@@ -0,0 +1,14 @@
+// Copyright 2019 Hans Dembinski
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/histogram/axis/integer.hpp>
+#include <boost/histogram/make_profile.hpp>
+
+int main() {
+  using namespace boost::histogram;
+  auto h = make_profile(axis::integer<>(0, 5));
+  h(0, sample(1, 2)); // weighted profile requires one sample
+}