Removed backprop operations (#1091)

* Removed backprop operations

* Fixed build

* Removed AvgPool

* Removed tests for v0 AvgPool

* Fixed code style

* Fixed export

Author: ilyachur

ngraph/src/ngraph/CMakeLists.txt

@@ -589,8 +589,6 @@ set (SRC
     pass/nop_elimination.hpp
     pass/pass.cpp
     pass/pass.hpp
-    pass/opset0_downgrade.cpp
-    pass/opset0_downgrade.hpp
     pass/opset1_downgrade.cpp
     pass/opset1_downgrade.hpp
     pass/opset1_upgrade.cpp

ngraph/src/ngraph/builder/reshape.hpp

@@ -78,6 +78,7 @@ namespace ngraph
         ///
         /// \return     The squeezed node.
         ///
+        NGRAPH_API
         std::shared_ptr<Node> squeeze(const Output<Node>& value,
                                       std::vector<std::size_t> axes = {0});