Reimplement buffer tests (#1007)

* Reimplement buffer tests

Reintegrated and fixed test code for buffer tests buffer_read_half and
buffer_write_half tests.

Added mem_alloc_ref_flags test code, as was previously non-existent,
to test CL_MEM_ALLOC_HOST_PTR. This flag was otherwise untested and
as similar tests within the suite are used to test other cl_mem_flags
it has been assumed that this was the purpose of the test.

Fixes #439

Change-Id: I5accf986be7436d09377d0bfd7afd5de2235c329
Signed-off-by: Ellen Norris-Thompson <ellen.norris-thompson@arm.com>

* move mem_read_write_flags to a common function

Code under mem_*_flags tests have a lot of duplication, this is
the first step of moving test code to a common function.

Contributes #439

Signed-off-by: Ellen Norris-Thompson <ellen.norris-thompson@arm.com>

* move mem_write_only_flags test code to a common function

Code under mem_*_flags tests have a lot of duplication

Contributes #439

Signed-off-by: Ellen Norris-Thompson <ellen.norris-thompson@arm.com>

* move mem_read_only_flags test code to a common function

Code under mem_*_flags tests have a lot of duplication

Contributes #439

Signed-off-by: Ellen Norris-Thompson <ellen.norris-thompson@arm.com>

* move mem_copy_host_flags test code to a common function

Code under mem_*_flags tests have a lot of duplication, moved
mem_copy_host_flags code and rearranged function where appropriate

mem_ref_alloc_flags test also uses common function.

Contributes #439

Signed-off-by: Ellen Norris-Thompson <ellen.norris-thompson@arm.com>

* Remove unused NOT_IMPLEMENTED_TEST macro

This define is not in use anymore, since tests have been
reimplemented in #439. Tests should be working and implemented
or not registered.

Signed-off-by: Ellen Norris-Thompson <ellen.norris-thompson@arm.com>

test_common/harness/threadTesting.h

@@ -22,7 +22,6 @@
 #include <CL/opencl.h>
 #endif
 
-#define TEST_NOT_IMPLEMENTED -99
 #define TEST_SKIPPED_ITSELF -100
 
 typedef int (*basefn)(cl_device_id deviceID, cl_context context,