prime_mmap: Add new test for calling mmap() on dma-buf fds

This test has the following subtests:
 - test_correct for correctness of the data
 - test_map_unmap checks for mapping idempotency
 - test_reprime checks for dma-buf creation idempotency
 - test_forked checks for multiprocess access
 - test_refcounting checks for buffer reference counting
 - test_dup checks that dup()ing the fd works
 - test_userptr make sure it fails when mmaping due the lack of obj->base.filp
   in a userptr.
 - test_errors checks the error return values for failures
 - test_aperture_limit tests multiple buffer creation at the gtt aperture
   limit

v2 (Tiago): Removed pattern_check(), which was walking through a useless
iterator. Removed superfluous PROT_WRITE from gem_mmap, in test_correct().
Added binary file to .gitignore
v3 (Tiago): squash patch "prime_mmap: Test for userptr mmap" into this one.
v4 (Tiago): use synchronized userptr for testing. Add test for buffer
overlapping.

Signed-off-by: Rob Bradford <rob@linux.intel.com>
Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>

tests/Makefile.sources

@@ -100,6 +100,7 @@ TESTS_progs_M = \
 	pm_rps \
 	pm_rc6_residency \
 	pm_sseu \
+	prime_mmap \
 	prime_self_import \
 	template \
 	$(NULL)