Don't require explicit conversion in pairs in unordered's insert tests.

In the draft standard the std::pair constructor from another pair is
only considered when overloading if both members are implicitly
constructible to their corresponding members. This breaks one of the
unordered tests which required an explicit conversion, so change it to
only require an implicit conversion.

[SVN r70028]

test/unordered/insert_tests.cpp

@@ -372,10 +372,10 @@ void map_insert_range_test2(X*,
     std::cerr<<"map_insert_range_test2\n";
 
     typedef test::list<
-        std::pair<BOOST_DEDUCED_TYPENAME X::key_type const, int>
+        std::pair<BOOST_DEDUCED_TYPENAME X::key_type const, test::implicitly_convertible>
     > list;
     test::random_values<
-        boost::unordered_map<BOOST_DEDUCED_TYPENAME X::key_type, int>
+        boost::unordered_map<BOOST_DEDUCED_TYPENAME X::key_type, test::implicitly_convertible>
     > v(1000, generator);
     list l(v.begin(), v.end());