* onnx: fix build for CentOS 7.4
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: fix build for CentOS 7.4
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: compile fix for CentOS 7
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: unit-test compilation fixes for CentOS 7
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: unit-test compilation fixes for CentOS 7
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: fix 'add abc initializer' unit test
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: fix code style
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>