The fuzzing harnesses from #19143 don't compile on macOS. i.e building at 476436b2dec254bb988f8c7a6cbec1d7bb7cecfd:
```bash
In file included from test/fuzz/addition_overflow.cpp:7:
./test/fuzz/util.h:335:13: error: no matching function for call to 'AdditionOverflow'
        if (AdditionOverflow((uint64_t)fuzzed_file->m_offset, random_bytes.size())) {
            ^~~~~~~~~~~~~~~~
./test/fuzz/util.h:201:16: note: candidate template ignored: deduced conflicting types for parameter 'T' ('unsigned long long' vs. 'unsigned long')
NODISCARD bool AdditionOverflow(const T i, const T j) noexcept
               ^
./test/fuzz/util.h:346:13: error: no matching function for call to 'AdditionOverflow'
        if (AdditionOverflow(fuzzed_file->m_offset, n)) {
            ^~~~~~~~~~~~~~~~
./test/fuzz/util.h:201:16: note: candidate template ignored: deduced conflicting types for parameter 'T' ('long long' vs. 'long')
NODISCARD bool AdditionOverflow(const T i, const T j) noexcept
               ^
2 errors generated.

In file included from test/fuzz/buffered_file.cpp:9:
./test/fuzz/util.h:335:13: error: no matching function for call to 'AdditionOverflow'
        if (AdditionOverflow((uint64_t)fuzzed_file->m_offset, random_bytes.size())) {
            ^~~~~~~~~~~~~~~~
./test/fuzz/util.h:201:16: note: candidate template ignored: deduced conflicting types for parameter 'T' ('unsigned long long' vs. 'unsigned long')
NODISCARD bool AdditionOverflow(const T i, const T j) noexcept
               ^
./test/fuzz/util.h:346:13: error: no matching function for call to 'AdditionOverflow'
        if (AdditionOverflow(fuzzed_file->m_offset, n)) {
            ^~~~~~~~~~~~~~~~
./test/fuzz/util.h:201:16: note: candidate template ignored: deduced conflicting types for parameter 'T' ('long long' vs. 'long')
NODISCARD bool AdditionOverflow(const T i, const T j) noexcept
               ^
2 errors generated.
```
mode = "w";
            break;
        }
        case 3: {
            mode = "w+";
            break;
        }
        case 4: {
            mode = "a";
            break;
        }
        case 5: {
            mode = "a+";
            break;
        }
        }
#ifdef _GNU_SOURCE
        const cookie_io_functions_t io_hooks = {
            FuzzedFileProvider::read,
            FuzzedFileProvider::write,
            FuzzedFileProvider::seek,
            FuzzedFileProvider::close,
        };
        return fopencookie(this, mode.c_str(), io_hooks);
#else
        (void)mode;
        return nullptr;
#endif
    }
    static ssize_t read(void* cookie, char* buf, size_t size)