Remove compatibility api suite (#530)

The last test was also an almost-perfect duplicate of its sibling
in the non-compatibility suite. The only difference was the name
of the member of cl_image_desc used to point to the buffer/memory
object (which changed in 2.x).

We currently always build the conformance tests with the
headers configured for 2.2 (using the default value really) but I've
added code for the pre-2.x name as well for when CL_VERSION_2_0 isn't
defined in case we need it and to keep track of the distinction in that
test.

Contributes to #494.

Signed-off-by: Kevin Petit <kevin.petit@arm.com>

test_conformance/opencl_conformance_tests_full.csv

@@ -94,7 +94,6 @@ Half Ops,half/test_half
 # Compatibility with Previous Versions
 # #########################################
 Basic 1.2,compatibility/test_conformance/basic/test_basic
-API 1.2,compatibility/test_conformance/api/test_api
 
 #####################################
 # OpenCL 2.0 tests