driver_vive: fix infinite loop when closing HIDAPI devices

[m-va]

Fixes #312.

Problem

On Windows, USE_HIDAPI defaults to ON, and survive_vive_close() never
returns:

while (sv->udev_cnt) {          // never reaches 0
#ifndef HIDAPI
    libusb_handle_events(sv->usbctx);
#endif
    for (int i = 0; i < sv->udev_cnt; i++) {
        if (survive_handle_close_request_flag(sv->udev[i])) i--;
    }
}

survive_handle_close_request_flag() only acts when usbInfo->request_close
is set. In the HIDAPI backend that flag is raised only in HAPIReceiver() when
hid_read() returns a negative value; survive_close_usb_device() closes the
HID handles without setting it. The libusb backend is unaffected because
libusb_handle_events() drives the completion callbacks that raise the flag,
and that call is #ifndef HIDAPI.

Besides hanging the process, this also means config_save() — which runs later
inside survive_close() — is never reached, so lighthouse calibration is never
written to config.json and has to be redone on every launch.

Fix

Raise the flag (and mark the interfaces shut down, mirroring the libusb path)
when the device is actually closed. Freeing the handle there is safe because
survive_usb_handle_close() is a no-op in this backend.

Testing

Windows 11 x64, MSVC, master, USE_HIDAPI=ON, two Vive Trackers (2018) over
USB with SteamVR 2.0 base stations:

• before: survive_simple_close() did not return after 60 s; config.json
  never contained lighthouse0/lighthouse1
• after: it returns immediately, and config.json gets the lighthouse entries,
  so a second launch starts tracking without recalibrating

[bl4ckb0ne]

Why was this closed @m-va ?

[m-va]

Sorry for the confusion — this was my mistake. I deleted my fork because I
misunderstood how forks are presented on GitHub, and that automatically closed
this PR. It was not intentional, and nothing is wrong with the patch itself.

Since the head repository is gone this PR can't be reopened, so I've re-forked
and will open a fresh PR with the same commit shortly. Apologies for the noise.