Stop using ../../test_common to include common headers

Fixes #395.

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

test_conformance/images/clFillImage/main.cpp

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 //
-#include "../../../test_common/harness/compat.h"
+#include "../harness/compat.h"
 
 #include <stdio.h>
 #include <string.h>
@@ -24,7 +24,7 @@
 #endif
 
 #include "../testBase.h"
-#include "../../../test_common/harness/testHarness.h"
+#include "../harness/testHarness.h"
 
 bool gDebugTrace;
 bool gTestSmallImages;