[libc++] Fixes (|multi)_set spaceship operator. (#127326)

The operators did not have a _Compare template arguement. The fix
updates the generic container test to use allocators for all types used.
No other issues were found.

Fixes: #127095
(cherry picked from commit 248716f)

Author: mordante

libcxx/include/set

@@ -1003,9 +1003,9 @@ operator<=(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare,
 
 #  else // _LIBCPP_STD_VER <= 17
 
-template <class _Key, class _Allocator>
+template <class _Key, class _Compare, class _Allocator>
 _LIBCPP_HIDE_FROM_ABI __synth_three_way_result<_Key>
-operator<=>(const set<_Key, _Allocator>& __x, const set<_Key, _Allocator>& __y) {
+operator<=>(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
   return std::lexicographical_compare_three_way(__x.begin(), __x.end(), __y.begin(), __y.end(), std::__synth_three_way);
 }
 
@@ -1470,9 +1470,9 @@ operator<=(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key,
 
 #  else // _LIBCPP_STD_VER <= 17
 
-template <class _Key, class _Allocator>
+template <class _Key, class _Compare, class _Allocator>
 _LIBCPP_HIDE_FROM_ABI __synth_three_way_result<_Key>
-operator<=>(const multiset<_Key, _Allocator>& __x, const multiset<_Key, _Allocator>& __y) {
+operator<=>(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {
   return std::lexicographical_compare_three_way(__x.begin(), __x.end(), __y.begin(), __y.end(), __synth_three_way);
 }