COMPMID-417 Checking CL non uniform support at runtime.

What have been done in the ticket are:
1. Add support to check whether cl-non-unform-workgroup is supported at
runtime
2. Add helper function to check the CL version at runtime
3. Add boolen to check whether CLSecheduler's init has been called.

Change-Id: I6e6df8eb5cebfac7229aa406242bb183477fd191
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/80265
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
diff --git a/arm_compute/core/CL/CLHelpers.h b/arm_compute/core/CL/CLHelpers.h
index 5234ae1..01980d9 100644
--- a/arm_compute/core/CL/CLHelpers.h
+++ b/arm_compute/core/CL/CLHelpers.h
@@ -102,5 +102,20 @@
  * @return the GPU target which shows the arch
  */
 GPUTarget get_arch_from_target(GPUTarget target);
+
+/** Helper function to get the highest OpenCL version supported
+ *
+ * @param[in] device A CL device
+ *
+ * @return the highest OpenCL version supported
+ */
+CLVersion get_cl_version(const cl::Device &device);
+/** Helper function to check whether the arm_non_uniform_work_group_size extension is supported
+ *
+ * @param[in] device A CL device
+ *
+ * @return True if the extension is supported
+ */
+bool non_uniform_workgroup_support(const cl::Device &device);
 }
 #endif /* __ARM_COMPUTE_CLHELPERS_H__ */
diff --git a/arm_compute/core/CL/CLTypes.h b/arm_compute/core/CL/CLTypes.h
index c5643d8..cf11f6e 100644
--- a/arm_compute/core/CL/CLTypes.h
+++ b/arm_compute/core/CL/CLTypes.h
@@ -37,5 +37,15 @@
     T800          = 0x130,
     G70           = 0x210
 };
+
+/* Available OpenCL Version */
+enum class CLVersion
+{
+    CL10,   /* the OpenCL 1.0 */
+    CL11,   /* the OpenCL 1.1 */
+    CL12,   /* the OpenCL 1.2 */
+    CL20,   /* the OpenCL 2.0 and above */
+    UNKNOWN /* unkown version */
+};
 }
 #endif /* __ARM_COMPUTE_CL_TYPES_H__ */
diff --git a/arm_compute/runtime/CL/CLScheduler.h b/arm_compute/runtime/CL/CLScheduler.h
index 8e80259..3f3a8de 100644
--- a/arm_compute/runtime/CL/CLScheduler.h
+++ b/arm_compute/runtime/CL/CLScheduler.h
@@ -72,9 +72,10 @@
     void init(cl::Context context = cl::Context::getDefault(), cl::CommandQueue queue = cl::CommandQueue::getDefault(),
               cl::Device device = cl::Device::getDefault())
     {
-        _context = std::move(context);
-        _queue   = std::move(queue);
-        _target  = get_target_from_device(device);
+        _context        = std::move(context);
+        _queue          = std::move(queue);
+        _target         = get_target_from_device(device);
+        _is_initialised = true;
     }
 
     /** Accessor for the associated CL context.
@@ -83,6 +84,7 @@
      */
     cl::Context &context()
     {
+        ARM_COMPUTE_ERROR_ON(!_is_initialised);
         return _context;
     }
 
@@ -101,6 +103,7 @@
      */
     cl::CommandQueue &queue()
     {
+        ARM_COMPUTE_ERROR_ON(!_is_initialised);
         return _queue;
     }
 
@@ -153,6 +156,7 @@
     cl::Context      _context;
     cl::CommandQueue _queue;
     GPUTarget        _target;
+    bool             _is_initialised;
 };
 }
 #endif /* __ARM_COMPUTE_CLSCHEDULER_H__ */