COMPMID-2941 Add QAsymm8 and S32 support for ArgMinMax to CL

Select operation does not work with any combination of datatypes.
Added a new OpenCL build option, DATA_TYPE_SELECT, in oder to
specify the select result.

Change-Id: I5c73c2a6b1d121288b7f6edba3e0cb1104636844
Signed-off-by: Michalis Spyrou <michalis.spyrou@arm.com>
Reviewed-on: https://review.mlplatform.org/c/2601
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
diff --git a/arm_compute/core/CL/CLHelpers.h b/arm_compute/core/CL/CLHelpers.h
index 4c9cfff..4b9ca4d 100644
--- a/arm_compute/core/CL/CLHelpers.h
+++ b/arm_compute/core/CL/CLHelpers.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2019 ARM Limited.
+ * Copyright (c) 2016-2020 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -66,6 +66,14 @@
  */
 std::string get_cl_unsigned_type_from_element_size(size_t element_size);
 
+/** Translates the element size to an signed integer data type
+ *
+ * @param[in] element_size Size in bytes of an element.
+ *
+ * @return The string specifying the OpenCL type to be used.
+ */
+std::string get_cl_signed_type_from_element_size(size_t element_size);
+
 /** Translates a tensor data type to the appropriate OpenCL select type.
  *
  * @param[in] dt @ref DataType to be translated to OpenCL select type.