Merge bitcoin#29859: build: Fix false positive CHECK_ATOMIC test

dd3e0fa build: Fix false positive `CHECK_ATOMIC` test for clang-15 (Hennadii Stepanov)

Pull request description:

  On the master branch @ 0de63b8, a building `bitcoind` with clang-15 for `i686-pc-linux-gnu` fails to link:
  ```
    CXXLD    bitcoind
  /usr/bin/ld: libbitcoin_wallet.a(libbitcoin_wallet_a-wallet.o): in function `std::remove_volatile<double>::type std::__atomic_impl::load<double>(double const*, std::memory_order)':
  /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:948: undefined reference to `__atomic_load'
  /usr/bin/ld: libbitcoin_wallet.a(libbitcoin_wallet_a-wallet.o): in function `void std::__atomic_impl::store<double>(double*, std::remove_volatile<double>::type, std::memory_order)':
  /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: undefined reference to `__atomic_store'
  /usr/bin/ld: libbitcoin_wallet.a(libbitcoin_wallet_a-wallet.o): in function `void std::__atomic_impl::store<double>(double*, std::remove_volatile<double>::type, std::memory_order)':
  /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: undefined reference to `__atomic_store'
  /usr/bin/ld: /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: undefined reference to `__atomic_store'
  /usr/bin/ld: libbitcoin_wallet.a(libbitcoin_wallet_a-wallet.o): in function `std::remove_volatile<double>::type std::__atomic_impl::load<double>(double const*, std::memory_order)':
  /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:948: undefined reference to `__atomic_load'
  /usr/bin/ld: libbitcoin_wallet.a(libbitcoin_wallet_a-wallet.o): in function `void std::__atomic_impl::store<double>(double*, std::remove_volatile<double>::type, std::memory_order)':
  /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: undefined reference to `__atomic_store'
  /usr/bin/ld: libbitcoin_wallet.a(libbitcoin_wallet_a-backup.o): in function `void std::__atomic_impl::store<double>(double*, std::remove_volatile<double>::type, std::memory_order)':
  /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: undefined reference to `__atomic_store'
  /usr/bin/ld: /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: undefined reference to `__atomic_store'
  /usr/bin/ld: /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: undefined reference to `__atomic_store'
  /usr/bin/ld: /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: undefined reference to `__atomic_store'
  /usr/bin/ld: libbitcoin_wallet.a(libbitcoin_wallet_a-backup.o):/usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/atomic_base.h:940: more undefined references to `__atomic_store' follow
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  ```

  due to false positive `CHECK_ATOMIC` test in the `configure` script.

  This PR fixes this test.

ACKs for top commit:
  maflcko:
    review ACK dd3e0fa
  fanquake:
    ACK dd3e0fa

Tree-SHA512: b60acf8d83fc84cc3280d95028395d341ed9ed2fcf38ae0a101d50aa19cc35540e9763aa36668c4dc1e1bc7e1f33dbda0e662df39c9e414a284ef91d7fc55fba

build-aux/m4/l_atomic.m4

@@ -7,7 +7,7 @@ dnl warranty.
 # Clang, when building for 32-bit,
 # and linking against libstdc++, requires linking with
 # -latomic if using the C++ atomic library.
-# Can be tested with: clang++ test.cpp -m32
+# Can be tested with: clang++ -std=c++20 test.cpp -m32
 #
 # Sourced from http://bugs.debian.org/797228
 
@@ -27,8 +27,11 @@ m4_define([_CHECK_ATOMIC_testbody], [[
     auto t1 = t.load();
     t.compare_exchange_strong(t1, 3s);
 
-    std::atomic<int64_t> a{};
+    std::atomic<double> d{};
+    d.store(3.14);
+    auto d1 = d.load();
 
+    std::atomic<int64_t> a{};
     int64_t v = 5;
     int64_t r = a.fetch_add(v);
     return static_cast<int>(r);