libstdc++: Simplify copy-pasted algorithms in <ranges>

The <ranges> header currently copies some simple algorithms from
<bits/ranges_algo.h>, which was originally done in order to avoid a
circular dependency with the header.  This is no longer an issue since
the latter header now includes <bits/ranges_util.h> instead of all of
<ranges>.

This means we could now just include <bits/ranges_algo.h> and remove the
copied algorithms, but that'd increase the size of <ranges> by ~10%.
And we can't use the corresponding STL-style algorithms here because
they assume input iterators are copyable.  So this patch instead
simplifies these copied algorithms, removing their constraints and
unused parameters, and keeps them around.  In a subsequent patch we're
going to copy (a simplified version of) ranges::find into <ranges> as
well.

libstdc++-v3/ChangeLog:

	* include/std/ranges (__detail::find_if): Simplify.
	(__detail::find_if_not): Likewise.
	(__detail::min): Remove.
	(__detail::mismatch): Simplify.
	(take_view::size): Use std::min instead of __detail::min.