Merge pull request #16724 from liqi-c:3.4-tengine

* Add Tengine support .

* Modify printf to CV_LOG_WARNING

* a few minor fixes in the code

* Renew Tengine version

* Add header file for CV_LOG_WARNING

* Add #ifdef HAVE_TENGINE in tengine_graph_convolution.cpp

* remove trailing whitespace

* Remove trailing whitespace

* Modify for compile problem

* Modify some code style error

* remove whitespace

* Move some code style problem

* test

* add ios limit and build problem

* Modified as alalek suggested

* Add cmake 2.8 support

* modify cmake 3.5.1 problem

* test and set BUILD_ANDROID_PROJECTS OFF

* remove some compile error

* remove some extra code in tengine

* close test.

* Test again

* disable android.

* delete ndk version judgement

* Remove setenv() call . and add License information

* Set tengine default OFF. Close test .

Co-authored-by: Vadim Pisarevsky <vadim.pisarevsky@gmail.com>

cmake/OpenCVFindTengine.cmake

@@ -0,0 +1,65 @@
+# COPYRIGHT
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# License); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# AS IS BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+# Copyright (c) 2020, OPEN AI LAB
+# Author: qtang@openailab.com or https://github.com/BUG1989
+#
+
+# ----------------------------------------------------------------------------
+#  Path for Tengine modules
+# ----------------------------------------------------------------------------
+set(OPENCV_LIBTENGINE_ROOT_DIR "" CACHE PATH "Where to look for additional OpenCV modules (can be ;-separated list of paths)")
+
+IF(OPENCV_LIBTENGINE_ROOT_DIR)
+
+	MESSAGE(STATUS "TENGINE:--  Set tengine lib dir by user ")
+
+	SET(Tengine_FOUND ON)
+	set(BUILD_TENGINE OFF)
+
+	SET(Tengine_INCLUDE_DIR   	${OPENCV_LIBTENGINE_ROOT_DIR}/include)
+	SET(Tengine_LIB 	${OPENCV_LIBTENGINE_ROOT_DIR}/lib/libtengine.a)
+
+ELSE()
+
+	MESSAGE(STATUS "TENGINE:--  Auto download Tengine source code. ")
+	include("${OpenCV_SOURCE_DIR}/3rdparty/libtengine/tengine.cmake")
+
+ENDIF()
+
+IF(NOT Tengine_LIB)
+	SET(Tengine_FOUND OFF)
+	MESSAGE(STATUS "#### Could not find Tengine lib. Turning Tengine_FOUND off")
+ENDIF()
+
+IF (Tengine_FOUND)
+	MESSAGE(STATUS "Found Tengine include: ${Tengine_INCLUDE_DIR}")
+	MESSAGE(STATUS "Found Tengine libraries: ${Tengine_LIB}")
+	set(HAVE_TENGINE 1)
+	set(TENGINE_LIBRARIES    ${Tengine_LIB})
+	set(TENGINE_INCLUDE_DIRS    ${Tengine_INCLUDE_DIR})
+ENDIF (Tengine_FOUND)
+
+MESSAGE(STATUS "Tengine include is:" ${Tengine_INCLUDE_DIR})
+MESSAGE(STATUS "Tengine library is:" ${Tengine_LIB})
+
+MARK_AS_ADVANCED(
+	Tengine_INCLUDE_DIR
+	Tengine_LIB
+	Tengine
+)