fileMemoryMapDestroy

fn fileMemoryMapDestroy(userdata: ?*anyopaque, mm: *File.MemoryMap) void {
    const t: *Threaded = @ptrCast(@alignCast(userdata));
    const memory = mm.memory;
    if (mm.section) |section| switch (native_os) {
        .windows => {
            if (section == windows.INVALID_HANDLE_VALUE) return;
            _ = windows.ntdll.NtUnmapViewOfSection(windows.current_process, memory.ptr);
            windows.CloseHandle(section);
        },
        .wasi => unreachable,
        else => {
            if (memory.len == 0) return;
            switch (posix.errno(posix.system.munmap(memory.ptr, memory.len))) {
                .SUCCESS => {},
                else => |e| {
                    if (builtin.mode == .debug)
                        std.log.err("failed to unmap {d} bytes at {*}: {t}", .{ memory.len, memory.ptr, e });
                },
            }
        },
    } else {
        const gpa = t.allocator;
        gpa.rawFree(memory, .fromByteUnits(std.heap.pageSize()), @returnAddress());
    }
    mm.* = undefined;
}