This PR adds negative tests for the following API functions:
- clCreateContext
- clCreateContextFromType
- clRetainContext
- clReleaseContext
- clSetContextDestructorCallback
Also, define a new macro `test_object_failure_ret` to test for an
expected error code and the returned object is `NULL` as a result of a
failure.
Signed-off-by: Michael Rizkalla <michael.rizkalla@arm.com>
