Minimized usage of IE_MAIN_SOURCE_DIR (#6422)

* Minimized IE_MAIN_SOURCE_DIR hardcode

* Used COMPILE_OPTIONS instead of COMPILE_FLAGS

* Fixed compilation

* Enabled NGRAPH_DYNAMIC_COMPONENTS_ENABLE by default

* Fixes

* Moved GNA related file

* Fixed backend compilation

* Fixed Windows for ngraph

* Fixed <root>/tests build

* More updates

* Fixed scripts install

* Fixed Windows

* Fixed Windows

inference-engine/samples/CMakeLists.txt

@@ -31,7 +31,7 @@ if (NOT BIN_FOLDER)
     endif()
 endif()
 
-if(IE_MAIN_SOURCE_DIR)
+if(OpenVINO_SOURCE_DIR)
     # in case if samples are built from IE repo
     set(IE_MAIN_SAMPLES_DIR ${OpenVINO_MAIN_SOURCE_DIR})
     # hint for find_package(InferenceEngine in the samples folder)
@@ -111,7 +111,7 @@ endif()
 ####################################
 
 if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/gflags" AND
-    NOT DEFINED IE_MAIN_SOURCE_DIR)
+    NOT DEFINED OpenVINO_SOURCE_DIR)
     function(add_gflags)
         # common gflags settings
         set(GFLAGS_IS_SUBPROJECT TRUE)
@@ -152,7 +152,7 @@ elseif(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/common/opencv_c_wrapper")
 endif()
 
 # samples build can be switched off during whole IE build
-if (DEFINED IE_MAIN_SOURCE_DIR AND NOT ENABLE_SAMPLES)
+if (DEFINED OpenVINO_SOURCE_DIR AND NOT ENABLE_SAMPLES)
     return()
 endif()