Tool which emits batch buffers to engines with configurable
sequences, durations, contexts, dependencies and userspace waits.

Unfinished but shows promise so sending out for early feedback.

v2:
 * Load workload descriptors from files. (also -w)
 * Help text.
 * Calibration control if needed. (-t)
 * NORELOC | LUT to eb flags.
 * Added sample workload to wsim/workload1.

v3:
 * Multiple parallel different workloads (-w -w ...).
 * Multi-context workloads.
 * Variable (random) batch length.
 * Load balancing (round robin and queue depth estimation).
 * Workloads delays and explicit sync steps.
 * Workload frequency (period) control.

v4:
 * Fixed queue-depth estimation by creating separate batches
   per engine when qd load balancing is on.
 * Dropped separate -s cmd line option. It can turn itself on
   automatically when needed.
 * Keep a single status page and lie about the write hazard
   as suggested by Chris.
 * Use batch_start_offset for controlling the batch duration.
   (Chris)
 * Set status page object cache level. (Chris)
 * Moved workload description to a README.
 * Tidied example workloads.
 * Some other cleanups and refactorings.

v5:
 * Master and background workloads (-W / -w).
 * Single batch per step is enough even when balancing. (Chris)
 * Use hars_petruska_f54_1_random IGT functions and see to zero
   at start. (Chris)
 * Use WC cache domain when WC mapping. (Chris)
 * Keep seqnos 64-bytes apart in the status page. (Chris)
 * Add workload throttling and queue-depth throttling commands.
   (Chris)

v6:
 * Added two more workloads.
 * Merged RT balancer from Chris.

v7:
 * Merged NO_RELOC patch from Chris.
 * Added missing RT balancer to help text.

TODO list:

 * Fence support.
 * Batch buffer caching (re-use pool).
 * Better error handling.
 * Less 1980's workload parsing.
 * More workloads.
 * Threads?
 * ... ?

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "Rogozhkin, Dmitry V" <dmitry.v.rogozhkin@intel.com>