libstdc++: Reduce header dependencies from PSTL headers [PR92546]

libstdc++: Reduce header dependencies from PSTL headers [PR92546]

This avoids including the whole of <functional> in <algorithm>, as the
<pstl/glue_algorithm_defs.h> header only actually needs std::pair.

This also avoids including <iterator> in <pstl/utils.h>, which only
needs <type_traits>, std::bad_alloc, and std::terminate (which can be
repalced with std::__terminate). This matters less, because
<pstl/utils.h> is only included by the <pstl/*_impl.h> headers and they
all use <iterator> anyway, and are only included by <execution>.

libstdc++-v3/ChangeLog:

	PR libstdc++/92546
	* include/pstl/glue_algorithm_defs.h: Replace <functional> with
	<bits/stl_pair.h>.
	* include/pstl/utils.h: Replace <iterator> with <type_traits>.
	(__pstl::__internal::__except_handler): Use std::__terminate
	instead of std::terminate.
	* src/c++17/fs_path.cc: Include <array>.
	* testsuite/25_algorithms/adjacent_find/constexpr.cc: Include
	<functional>.
	* testsuite/25_algorithms/binary_search/constexpr.cc: Likewise.
	* testsuite/25_algorithms/clamp/constrained.cc: Likewise.
	* testsuite/25_algorithms/equal/constrained.cc: Likewise.
	* testsuite/25_algorithms/for_each/constrained.cc: Likewise.
	* testsuite/25_algorithms/includes/constrained.cc: Likewise.
	* testsuite/25_algorithms/is_heap/constexpr.cc: Likewise.
	* testsuite/25_algorithms/is_heap_until/constexpr.cc: Likewise.
	* testsuite/25_algorithms/is_permutation/constrained.cc: Include
	<iterator>.
	* testsuite/25_algorithms/is_sorted/constexpr.cc: Include
	<functional>.
	* testsuite/25_algorithms/is_sorted_until/constexpr.cc:
	Likewise.
	* testsuite/25_algorithms/lexicographical_compare/constexpr.cc:
	Likewise.
	* testsuite/25_algorithms/lexicographical_compare/constrained.cc:
	Likewise.
	* testsuite/25_algorithms/lexicographical_compare_three_way/1.cc:
	Include <array>.
	* testsuite/25_algorithms/lower_bound/constexpr.cc: Include
	<functional>.
	* testsuite/25_algorithms/max/constrained.cc: Likewise.
	* testsuite/25_algorithms/max_element/constrained.cc: Likewise.
	* testsuite/25_algorithms/min/constrained.cc: Likewise.
	* testsuite/25_algorithms/min_element/constrained.cc: Likewise.
	* testsuite/25_algorithms/minmax_element/constrained.cc:
	Likewise.
	* testsuite/25_algorithms/mismatch/constexpr.cc: Likewise.
	* testsuite/25_algorithms/move/93872.cc: Likewise.
	* testsuite/25_algorithms/move_backward/93872.cc: Include
	<iterator>.
	* testsuite/25_algorithms/nth_element/constexpr.cc: Include
	<functional>.
	* testsuite/25_algorithms/partial_sort/constexpr.cc: Likewise.
	* testsuite/25_algorithms/partial_sort_copy/constexpr.cc:
	Likewise.
	* testsuite/25_algorithms/search/constexpr.cc: Likewise.
	* testsuite/25_algorithms/search_n/constrained.cc: Likewise.
	* testsuite/25_algorithms/set_difference/constexpr.cc: Likewise.
	* testsuite/25_algorithms/set_difference/constrained.cc:
	Likewise.
	* testsuite/25_algorithms/set_intersection/constexpr.cc:
	Likewise.
	* testsuite/25_algorithms/set_intersection/constrained.cc:
	Likewise.
	* testsuite/25_algorithms/set_symmetric_difference/constexpr.cc:
	Likewise.
	* testsuite/25_algorithms/set_union/constexpr.cc: Likewise.
	* testsuite/25_algorithms/set_union/constrained.cc: Likewise.
	* testsuite/25_algorithms/sort/constexpr.cc: Likewise.
	* testsuite/25_algorithms/sort_heap/constexpr.cc: Likewise.
	* testsuite/25_algorithms/transform/constrained.cc: Likewise.
	* testsuite/25_algorithms/unique/constexpr.cc: Likewise.
	* testsuite/25_algorithms/unique/constrained.cc: Likewise.
	* testsuite/25_algorithms/unique_copy/constexpr.cc: Likewise.
	* testsuite/25_algorithms/upper_bound/constexpr.cc: Likewise.
	* testsuite/std/ranges/adaptors/elements.cc: Include <vector>.
	* testsuite/std/ranges/adaptors/lazy_split.cc: Likewise.
	* testsuite/std/ranges/adaptors/split.cc: Likewise.