BSOD in Npcap 0.99 when suspending #390

Reported via Microsoft Hardware Dev Center crash telemetry.

When the Npcap driver's FILTER_PAUSE method is called, it puts the driver into the paused state, but if any NBLs are pending (packets waiting to be sent) they are sent anyway, and then NdisFPauseComplete is called, even though NPF_Pause already returned NDIS_STATUS_SUCCESS.

Instead, NPF_Pause should set the PausePending flag (as it does) and then wait until all NBLs are processed before returning NDIS_STATUS_SUCCESS.