Fix incorrect results from std::boyer_moore_searcher

	* include/std/functional (default_searcher, __boyer_moore_array_base)
	(__is_std_equal_to, __boyer_moore_base_t, boyer_moore_searcher)
	(boyer_moore_horspool_searcher): Remove redundant namespace
	qualification.
	(default_searcher::operator()): Construct return value early and
	advance second member in-place.
	(boyer_moore_horspool_searcher::operator()): Increment random access
	iterator directly instead of using std::next.
	(boyer_moore_searcher::operator()): Fix return value.
	* testsuite/20_util/function_objects/searchers.cc: Check both parts
	of return values.

From-SVN: r246964