feat: 切换后端至PaddleOCR-NCNN，切换工程为CMake

1.项目后端整体迁移至PaddleOCR-NCNN算法，已通过基本的兼容性测试
2.工程改为使用CMake组织，后续为了更好地兼容第三方库，不再提供QMake工程
3.重整权利声明文件，重整代码工程，确保最小化侵权风险

Log: 切换后端至PaddleOCR-NCNN，切换工程为CMake
Change-Id: I4d5d2c5d37505a4a24b389b1a4c5d12f17bfa38c

3rdparty/opencv-4.5.4/samples/android/tutorial-2-mixedprocessing/jni/Android.mk

@@ -0,0 +1,19 @@
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+
+ifdef OPENCV_ANDROID_SDK
+  ifneq ("","$(wildcard $(OPENCV_ANDROID_SDK)/OpenCV.mk)")
+    include ${OPENCV_ANDROID_SDK}/OpenCV.mk
+  else
+    include ${OPENCV_ANDROID_SDK}/sdk/native/jni/OpenCV.mk
+  endif
+else
+  include ../../sdk/native/jni/OpenCV.mk
+endif
+
+LOCAL_MODULE    := mixed_sample
+LOCAL_SRC_FILES := jni_part.cpp
+LOCAL_LDLIBS +=  -llog -ldl
+
+include $(BUILD_SHARED_LIBRARY)

3rdparty/opencv-4.5.4/samples/android/tutorial-2-mixedprocessing/jni/Application.mk

@@ -0,0 +1,4 @@
+APP_STL := gnustl_static
+APP_CPPFLAGS := -frtti -fexceptions
+APP_ABI := armeabi-v7a
+APP_PLATFORM := android-8

3rdparty/opencv-4.5.4/samples/android/tutorial-2-mixedprocessing/jni/CMakeLists.txt

@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.6)
+
+set(target mixed_sample)
+project(${target} CXX)
+
+set(ANDROID_OPENCV_COMPONENTS "opencv_java" CACHE STRING "")
+message(STATUS "ANDROID_ABI=${ANDROID_ABI}")
+find_package(OpenCV REQUIRED COMPONENTS ${ANDROID_OPENCV_COMPONENTS})
+
+file(GLOB srcs *.cpp *.c)
+file(GLOB hdrs *.hpp *.h)
+
+include_directories("${CMAKE_CURRENT_LIST_DIR}")
+add_library(${target} SHARED ${srcs} ${hdrs})
+target_link_libraries(${target} ${ANDROID_OPENCV_COMPONENTS})

3rdparty/opencv-4.5.4/samples/android/tutorial-2-mixedprocessing/jni/jni_part.cpp

@@ -0,0 +1,27 @@
+#include <jni.h>
+#include <opencv2/core.hpp>
+#include <opencv2/imgproc.hpp>
+#include <opencv2/features2d.hpp>
+#include <vector>
+
+using namespace std;
+using namespace cv;
+
+extern "C" {
+JNIEXPORT void JNICALL Java_org_opencv_samples_tutorial2_Tutorial2Activity_FindFeatures(JNIEnv*, jobject, jlong addrGray, jlong addrRgba);
+
+JNIEXPORT void JNICALL Java_org_opencv_samples_tutorial2_Tutorial2Activity_FindFeatures(JNIEnv*, jobject, jlong addrGray, jlong addrRgba)
+{
+    Mat& mGr  = *(Mat*)addrGray;
+    Mat& mRgb = *(Mat*)addrRgba;
+    vector<KeyPoint> v;
+
+    Ptr<FeatureDetector> detector = FastFeatureDetector::create(50);
+    detector->detect(mGr, v);
+    for( unsigned int i = 0; i < v.size(); i++ )
+    {
+        const KeyPoint& kp = v[i];
+        circle(mRgb, Point(kp.pt.x, kp.pt.y), 10, Scalar(255,0,0,255));
+    }
+}
+}