tests/gem_userptr_blits: Expanded userptr test cases

A set of userptr test cases to support the new feature.

For the eviction and swapping stress testing I have extracted
some common behaviour from gem_evict_everything and made both
test cases use it to avoid duplicating the code.

Both unsynchronized and synchronized userptr objects are
tested but the latter set of tests will be skipped if kernel
is compiled without MMU_NOTIFIERS.

Also, with 32-bit userspace swapping tests are skipped if
the system has a lot more RAM than process address space.
Forking swapping tests are not skipped since they can still
trigger swapping by cumulative effect.

v2:
   * Fixed dmabuf test.
   * Added test for rejecting read-only.
   * Fixed ioctl detection for latest kernel patch.

v3:
   * Use ALIGN macro.
   * Catchup with big lib/ reorganization.
   * Fixed up some warnings.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Brad Volkin <bradley.d.volkin@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

tests/.gitignore

@@ -98,6 +98,7 @@ gem_tiling_max_stride
 gem_unfence_active_buffers
 gem_unref_active_buffers
 gem_vmap_blits
+gem_userptr_blits
 gem_wait_render_timeout
 gem_write_read_ring_switch
 gen3_mixed_blits

tests/Makefile.sources

@@ -124,6 +124,7 @@ TESTS_progs = \
 	gem_unfence_active_buffers \
 	gem_unref_active_buffers \
 	gem_vmap_blits \
+	gem_userptr_blits \
 	gem_wait_render_timeout \
 	gen3_mixed_blits \
 	gen3_render_linear_blits \