Merge pull request #15419 from OrestChura:gapi_headers_internal_flag_issue

* - headers in "infer/" and "infer/ie/" folders are included into gapi_ext_hdrs;
+ because of that a few #includes are required in the headers
- HAVE_INF_ENGINE flag check in headers "infer/ie.hpp" and "infer/ie/util.hpp" is deleted

* - the "ie/util.hpp" header is a private header now as it's used for tests; it's been moved to the scr directory to the place next to the implementation file "ie/giebackend.cpp"
- the path to this header in files "ie/giebackend.cpp" and "test/infer/gapi_infer_ie_test.cpp" is updated
- As it's private header now and explicitly depends on IE, the "HAVE_INF_ENGINE" flag check is returned

modules/gapi/include/opencv2/gapi/infer/ie.hpp

@@ -7,8 +7,6 @@
 #ifndef OPENCV_GAPI_INFER_IE_HPP
 #define OPENCV_GAPI_INFER_IE_HPP
 
-#ifdef HAVE_INF_ENGINE
-
 #include <unordered_map>
 #include <string>
 #include <array>
@@ -17,6 +15,9 @@
 #include <opencv2/gapi/opencv_includes.hpp>
 #include <opencv2/gapi/util/any.hpp>
 
+#include <opencv2/core/cvdef.h>     // GAPI_EXPORTS
+#include <opencv2/gapi/gkernel.hpp> // GKernelPackage
+
 namespace cv {
 namespace gapi {
 // FIXME: introduce a new sub-namespace for NN?
@@ -101,6 +102,4 @@ protected:
 } // namespace gapi
 } // namespace cv
 
-#endif // HAVE_INF_ENGINE
-
 #endif // OPENCV_GAPI_INFER_HPP

modules/gapi/include/opencv2/gapi/infer/ie/util.hpp

@@ -1,31 +0,0 @@
-// This file is part of OpenCV project.
-// It is subject to the license terms in the LICENSE file found in the top-level directory
-// of this distribution and at http://opencv.org/license.html.
-//
-// Copyright (C) 2019 Intel Corporation
-
-#ifndef OPENCV_GAPI_INFER_IE_UTIL_HPP
-#define OPENCV_GAPI_INFER_IE_UTIL_HPP
-
-#ifdef HAVE_INF_ENGINE
-
-// NOTE: This file is not included by default in infer/ie.hpp
-// and won't be. infer/ie.hpp doesn't depend on IE headers itself.
-// This file does -- so needs to be included separately by those who care.
-
-#include "inference_engine.hpp"
-
-namespace cv {
-namespace gapi {
-namespace ie {
-namespace util {
-
-GAPI_EXPORTS std::vector<int> to_ocv(const InferenceEngine::SizeVector &dims);
-
-GAPI_EXPORTS cv::Mat to_ocv(InferenceEngine::Blob::Ptr blob);
-GAPI_EXPORTS InferenceEngine::Blob::Ptr to_ie(cv::Mat &blob);
-
-}}}}
-
-#endif // HAVE_INF_ENGINE
-#endif // OPENCV_GAPI_INFER_IE_UTIL_HPP