eal: add failure handling for hot-unplug

eal: add failure handling for hot-unplug

The mechanism can initially register the sigbus handler after the device
event monitor is enabled. When a sigbus event is captured, it will check
the failure address and accordingly handle the memory failure of the
corresponding device by invoke the hot-unplug handler. It could prevent
the application from crashing when a device is hot-unplugged.

By this patch, users could call below new added APIs to enable/disable
the device hotplug handle mechanism. Note that it just implement the
hot-unplug handler in these functions, the other handler of hotplug, such
as handler for hotplug binding, could be add in the future if need:
  - rte_dev_hotplug_handle_enable
  - rte_dev_hotplug_handle_disable

Signed-off-by: Jeff Guo <jia.guo@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>