Add move-function for sc_usb_device

Add a function to "move" a sc_usb_device into another instance.

This will avoid unnecessary copies.

PR #3005 <https://github.com/Genymobile/scrcpy/pull/3005>

app/src/usb/usb.c

@@ -72,12 +72,23 @@ accept_device(libusb_device *device, const char *serial,
 
 void
 sc_usb_device_destroy(struct sc_usb_device *usb_device) {
-    libusb_unref_device(usb_device->device);
+    if (usb_device->device) {
+        libusb_unref_device(usb_device->device);
+    }
     free(usb_device->serial);
     free(usb_device->manufacturer);
     free(usb_device->product);
 }
 
+void
+sc_usb_device_move(struct sc_usb_device *dst, struct sc_usb_device *src) {
+    *dst = *src;
+    src->device = NULL;
+    src->serial = NULL;
+    src->manufacturer = NULL;
+    src->product = NULL;
+}
+
 void
 sc_usb_devices_destroy_all(struct sc_usb_device *usb_devices, size_t count) {
     for (size_t i = 0; i < count; ++i) {

app/src/usb/usb.h

@@ -40,6 +40,18 @@ struct sc_usb_device {
 void
 sc_usb_device_destroy(struct sc_usb_device *usb_device);
 
+/**
+ * Move src to dst
+ *
+ * After this call, the content of src is undefined, except that
+ * sc_usb_device_destroy() can be called.
+ *
+ * This is useful to take a device from a list that will be destroyed, without
+ * making unnecessary copies.
+ */
+void
+sc_usb_device_move(struct sc_usb_device *dst, struct sc_usb_device *src);
+
 void
 sc_usb_devices_destroy_all(struct sc_usb_device *usb_devices, size_t count);