add device removal event

This new event represents the sudden removal of a device from its bus. The underlying resources exposed by the bus are expected not to be available anymore. The application should thus be able to react and possibly clean up related resources that it reserved for the removed device.

This event is different from the current hotplug API available in the DPDK for two reasons:

1. It is a reactive design: the application reacts to a device that has been removed instead of removing a device from its pool.

2. The event itself is going further than the current detaching of a device from a DPDK application. If the bus is a hardware one, it is expected of the underlying resources to not be available anymore.

This series adds a new event type to ethdev and implements it in mlx4. Testpmd is also updated to report all asynchronous ethdev events including this one for testing purposes and as a practical usage example.

This series depends on the series titled
[PATCH 1/2] net/mlx4: split the definitions to the header file

v1 --> v2:
* integrated the series with the new PCI rte_bus implementation.

I planned on working out a more generic implementation of the RMV event for the v17.05, however while writing it I found that I had to evolve the support of interrupts in the PCI rte_bus, which did not seem wise at this point of the release cycle.

I consider that this event should be generalized along the LSC event, going from pure PCI events to generic rte_bus events, given that they can be relevant to other busses (vdev at least). I would reserve this evolution for future release however, once a real discussion has taken place.

Gaetan Rivet (5):
ethdev: introduce device removal event
net/mlx4: device removal event support
app/testpmd: generic event handler
app/testpmd: request link status interrupt
app/testpmd: request device removal interrupt

 app/test-pmd/parameters.c                       |   8 +
 app/test-pmd/testpmd.c                          | 103 ++++++++++
 app/test-pmd/testpmd.h                          |   2 +
 doc/guides/nics/features/default.ini            |   1 +
 doc/guides/nics/features/mlx4.ini               |   1 +
 doc/guides/prog_guide/env_abstraction_layer.rst |  21 +-
 drivers/net/mlx4/mlx4.c                         | 258 ++++++++++++++++++++----
 drivers/net/mlx4/mlx4.h                         |   1 +
 lib/librte_eal/common/include/rte_pci.h         |   2 +
 lib/librte_ether/rte_ethdev.c                   |  11 +-
 lib/librte_ether/rte_ethdev.h                   |   9 +-
 lib/librte_ether/rte_ethdev_pci.h               |   2 +
 12 files changed, 375 insertions(+), 44 deletions(-)

2.1.4