COMPMID-2549: Add GLES Runtime Context interfaces.

* Creates interfaces and concrete classes
* Ports GCActivationalLayer
* Adapts test framework and relevant tests

Change-Id: Ide36cd65ebf185958db3c4a5bebd630fcb2f39b3
Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/2199
Reviewed-by: Pablo Marquez <pablo.tello@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/runtime/CL/ICLSimpleFunction.h b/arm_compute/runtime/CL/ICLSimpleFunction.h
index 8399a3d..5b6b608 100644
--- a/arm_compute/runtime/CL/ICLSimpleFunction.h
+++ b/arm_compute/runtime/CL/ICLSimpleFunction.h
@@ -32,7 +32,9 @@
 
 namespace arm_compute
 {
+// Forward declarations
 class CLRuntimeContext;
+
 /** Basic interface for functions which have a single OpenCL kernel */
 class ICLSimpleFunction : public IFunction
 {
@@ -60,5 +62,5 @@
     CLFillBorderKernel         _border_handler; /**< Kernel to handle  borders */
     CLRuntimeContext          *_ctx;            /**< Context to use */
 };
-}
+} // namespace arm_compute
 #endif /*__ARM_COMPUTE_ICLSIMPLEFUNCTION_H__ */