Add execution environment.

- this class will encapsulate common shared state
- platform will create it
- clients will increment ref count
- platform upon destruction will decrement ref counts
- it means that execution environment will be capable of living longer then
platform in case there will be dependencies.

Change-Id: I0ea7f85ea57448c0e641673f1d15851e50b2b8b2

runtime/execution_environment/execution_environment.h

@@ -0,0 +1,28 @@
+/*
+* Copyright (c) 2018, Intel Corporation
+*
+* Permission is hereby granted, free of charge, to any person obtaining a
+* copy of this software and associated documentation files (the "Software"),
+* to deal in the Software without restriction, including without limitation
+* the rights to use, copy, modify, merge, publish, distribute, sublicense,
+* and/or sell copies of the Software, and to permit persons to whom the
+* Software is furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+* OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include "runtime/utilities/reference_tracked_object.h"
+
+namespace OCLRT {
+class ExecutionEnvironment : public ReferenceTrackedObject<ExecutionEnvironment> {
+};
+} // namespace OCLRT