COMPMID-601: Add GraphContext

GraphContext hold all the information about the hints that need to be
passed in the nodes. As these might expand, it serves as a centralized
class for such information.

Change-Id: I0b5527630fb97cc5fa500db0bac8307ff2ea36e6
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/90300
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
diff --git a/arm_compute/graph/Types.h b/arm_compute/graph/Types.h
index 538d64e..e48ff84 100644
--- a/arm_compute/graph/Types.h
+++ b/arm_compute/graph/Types.h
@@ -47,7 +47,7 @@
 using arm_compute::PoolingType;
 
 /**< Execution hint to the graph executor */
-enum class Hint
+enum class TargetHint
 {
     DONT_CARE, /**< Run node in any device */
     OPENCL,    /**< Run node on an OpenCL capable device (GPU) */