[libc++] Fix copy/pasta error in atomic tests for atomic_compare_exchange_{weak,strong} (#87135)

Spotted this minor mistake in the tests as I was looking into testing
more thoroughly `atomic_ref`.

The two argument overloads are tested just above. The names of the
lambda clearly indicates that the intent was to test the one argument
overload.

Author: dalg24

libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_strong.pass.cpp

@@ -150,12 +150,12 @@ void test_impl() {
     test_seq_cst<T, MaybeVolatile>(store, load);
 
     auto store_one_arg = [](MaybeVolatile<std::atomic<T>>& x, T old_val, T new_val) {
-      auto r = x.compare_exchange_strong(old_val, new_val, std::memory_order::seq_cst, std::memory_order_relaxed);
+      auto r = x.compare_exchange_strong(old_val, new_val, std::memory_order::seq_cst);
       assert(r);
     };
     auto load_one_arg = [](MaybeVolatile<std::atomic<T>>& x) {
       auto val = x.load(std::memory_order::relaxed);
-      while (!x.compare_exchange_strong(val, val, std::memory_order::seq_cst, std::memory_order_relaxed)) {
+      while (!x.compare_exchange_strong(val, val, std::memory_order::seq_cst)) {
       }
       return val;
     };

libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/compare_exchange_weak.pass.cpp

@@ -165,12 +165,12 @@ void test_impl() {
 
     auto store_one_arg = [](MaybeVolatile<std::atomic<T>>& x, T old_val, T new_val) {
       // could fail spuriously, so put it in a loop
-      while (!x.compare_exchange_weak(old_val, new_val, std::memory_order::seq_cst, std::memory_order_relaxed)) {
+      while (!x.compare_exchange_weak(old_val, new_val, std::memory_order::seq_cst)) {
       }
     };
     auto load_one_arg = [](MaybeVolatile<std::atomic<T>>& x) {
       auto val = x.load(std::memory_order::relaxed);
-      while (!x.compare_exchange_weak(val, val, std::memory_order::seq_cst, std::memory_order_relaxed)) {
+      while (!x.compare_exchange_weak(val, val, std::memory_order::seq_cst)) {
       }
       return val;
     };