functional (tr1_hashtable_define_trivial_hash): Make hash<T>::operator() a const member function for T a fundamental type

* include/tr1/functional (tr1_hashtable_define_trivial_hash): Make
hash<T>::operator() a const member function for T a fundamental type
* include/tr1/hashtable (extract1st::operator()): Declare const.
(hash_code_base): Declare all member functions const
(hashtable::find): fix call to this->bucket_count()
(hashtable::count): Likewise.
(hashtable::equal_range): m_incr_bucket applies to iterator, not node.
* testsuite/tr1/6_containers/unordered/find/set1.cc: New test.
* testsuite/tr1/6_containers/unordered/find/map1.cc: New test.
* testsuite/tr1/6_containers/unordered/find/multimap1.cc: New test.
* testsuite/tr1/6_containers/unordered/find/multiset1.cc: New test.

From-SVN: r95293