COMPMID-545 add CL printf support

Change-Id: I685a68e7bc8d2cdff19851d839f244206b3d5790
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/89391
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
diff --git a/src/core/CL/cl_kernels/helpers.h b/src/core/CL/cl_kernels/helpers.h
index 68af64e..4421e74 100644
--- a/src/core/CL/cl_kernels/helpers.h
+++ b/src/core/CL/cl_kernels/helpers.h
@@ -25,6 +25,9 @@
 #define ARM_COMPUTE_HELPER_H
 
 #pragma OPENCL EXTENSION cl_khr_fp16 : enable
+#if defined(ARM_COMPUTE_DEBUG_ENABLED)
+#pragma OPENCL EXTENSION cl_arm_printf : enable
+#endif // defined(ARM_COMPUTE_DEBUG_ENABLED)
 
 #define EXPAND(x) x