Fix typo (KhronosGroup#321)

`CL_KHR_COMMAND_BUFFER_VERSION` is incorrect, should be
`CL_KHR_COMMAND_BUFFER_EXTENSION_VERSION` instead, which is defined in
`CL/cl_ext.h`. This fixes a compilation error seen with `-Wundef` and
`-Werror`.

Signed-off-by: Ahmed Hesham <ahmed.hesham@arm.com>

Author: ahesham-arm

include/CL/opencl.hpp

@@ -1867,7 +1867,7 @@ CL_HPP_DECLARE_PARAM_TRAITS_(cl_device_info, CL_DEVICE_INTEGRATED_MEMORY_NV, cl_
 
 #if defined(cl_khr_command_buffer)
 CL_HPP_DECLARE_PARAM_TRAITS_(cl_device_info, CL_DEVICE_COMMAND_BUFFER_CAPABILITIES_KHR, cl_device_command_buffer_capabilities_khr)
-#if CL_KHR_COMMAND_BUFFER_VERSION > CL_MAKE_VERSION(0, 9, 5)
+#if CL_KHR_COMMAND_BUFFER_EXTENSION_VERSION > CL_MAKE_VERSION(0, 9, 5)
 CL_HPP_DECLARE_PARAM_TRAITS_(
     cl_device_info, CL_DEVICE_COMMAND_BUFFER_SUPPORTED_QUEUE_PROPERTIES_KHR,
     cl_command_queue_properties)