Just a few basic tests to make sure fb modifiers can be used and
behave sanely when mixed with the old set_tiling API.
v2:
* Review feedback from Daniel Vetter:
1. Move cap detection into the subtest so skipping works.
2. Added some gtkdoc comments.
3. Two more test cases.
4. Removed unused parts for now.
v3:
* Removed two tests which do not make sense any more after the
fb modifier rewrite.
v4:
* Moved gtkdoc comments into .c file.
* Moved all initialization into fixtures.
* Rebased for fb modifier changes.
v5:
* Added bad modifier subtest.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>