When compiling without external signer support, the resulted `bench_bitcoin.exe` fails on Windows:
```
>.\bench_bitcoin.exe -filter=AddrManSelectByNetwork
Error: bad optional access
```

Steps to reproduce the failure:
- cross compiling on Ubuntu 22.04:
```
$ make -j $(nproc) -C depends HOST=x86_64-w64-mingw32 NO_QT=1
$ ./autogen.sh
$ ./configure CONFIG_SITE=$PWD/depends/x86_64-w64-mingw32/share/config.site --disable-external-signer
$ make -j $(nproc)
```
- compiling natively on Windows:

Apply the diff as follows:
```diff
--- a/build_msvc/bitcoin_config.h.in
+++ b/build_msvc/bitcoin_config.h.in
@@ -41,9 +41,6 @@
 /* Define this symbol to enable ZMQ functions */
 #define ENABLE_ZMQ 1
 
-/* define if external signer support is enabled (requires Boost::Process) */
-#define ENABLE_EXTERNAL_SIGNER /**/
-
 /* Define to 1 if you have the declaration of `be16toh', and to 0 if you
    don't. */
 #define HAVE_DECL_BE16TOH 0
```
Then
```
>py -3 build_msvc\msvc-autogen.py
>msbuild build_msvc\bitcoin.sln -property:Configuration=Release -verbosity:minimal
>src\bench_bitcoin.exe -filter=AddrManSelectByNetwork
Error: bad optional access
```

---

The failure does not manifest itself when running `bench_bitcoin.exe` using Wine on Linux.
{
    auto& chainman{*Assert(m_node.chainman)};
    node::ChainstateLoadOptions options;
    options.mempool = Assert(m_node.mempool.get());
    options.block_tree_db_in_memory = m_block_tree_db_in_memory;
    options.coins_db_in_memory = m_coins_db_in_memory;
    options.reindex = node::fReindex;
    options.reindex_chainstate = m_args.GetBoolArg("-reindex-chainstate", false);
    options.prune = chainman.m_blockman.IsPruneMode();
    options.check_blocks = m_args.GetIntArg("-checkblocks", DEFAULT_CHECKBLOCKS);
    options.check_level = m_args.GetIntArg("-checklevel", DEFAULT_CHECKLEVEL);
    options.require_full_verification = m_args.IsArgSet("-checkblocks") || m_args.IsArgSet("-checklevel");
    auto [status, error] = LoadChainstate(chainman, m_cache_sizes, options);
    assert(status == node::ChainstateLoadStatus::SUCCESS);
    std::tie(status, error) = VerifyLoadedChainstate(chainman, options);
    assert(status == node::ChainstateLoadStatus::SUCCESS);
    BlockValidationState state;
    if (!chainman.ActiveChainstate().ActivateBestChain(state)) {
        throw std::runtime_error(strprintf("ActivateBestChain failed. (%s)", state.ToString()));
    }
}
TestingSetup::TestingSetup(
    const ChainType chainType,