closed:
usbd_open_pipe_intr() allocates a usbd_xfer_handle for pipe->intrxfer.
Most usb device drivers using interrupt pipes call usbd_abort_pipe()
then usbd_close_pipe(), usbd_close_pipe() is supposed to free pipe->intrxfer.
But usbd_abort_pipe() calls [uoe]hci_device_intr_abort() which,
if the xfer aborted is pipe's intrxfer, sets pipe->intrxfer to NULL.
So usbd_close_pipe() can't free it and the usbd_xfer_handle is lost.
To fix this, in usbd_abort_pipe() remember the pipe->intrxfer's value
on entrie, and if it's different after usbd_ar_pipe(), call
usbd_free_xfer with the original value.
Confirmed to fix the memory leak on close() with umodem(4) and
uplcom(4).
8189b574e4