报错了，找不到原因，求大佬提点一下 #4
Description
Build command failed.
Error while executing process H:\Android\sdk\cmake\3.6.4111459\bin\cmake.exe with arguments {--build H:\opencv\OpenCV4Android-master\app.externalNativeBuild\cmake\debug\arm64-v8a --target opencv341}
[1/2] Building CXX object CMakeFiles/opencv341.dir/src/main/cpp/DetectionBasedTracker_jni.cpp.o
[2/2] Linking CXX shared library ........\build\intermediates\cmake\debug\obj\arm64-v8a\libopencv341.so
FAILED: cmd.exe /C "cd . && H:\Android\sdk\ndk-bundle\toolchains\llvm\prebuilt\windows-x86_64\bin\clang++.exe --target=aarch64-none-linux-android --gcc-toolchain=H:/Android/sdk/ndk-bundle/toolchains/aarch64-linux-android-4.9/prebuilt/windows-x86_64 --sysroot=H:/Android/sdk/ndk-bundle/sysroot -fPIC -isystem H:/Android/sdk/ndk-bundle/sysroot/usr/include/aarch64-linux-android -D__ANDROID_API__=21 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -Wa,--noexecstack -Wformat -Werror=format-security -std=c++11 -std=c++11 -frtti -fexceptions -std=gnu++11 -fexceptions -frtti -O2 -DNDEBUG -Wl,--exclude-libs,libgcc.a -Wl,--exclude-libs,libatomic.a -nostdlib++ --sysroot H:/Android/sdk/ndk-bundle/platforms/android-21/arch-arm64 -Wl,--build-id -Wl,--warn-shared-textrel -Wl,--fatal-warnings -LH:/Android/sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/libs/arm64-v8a -Wl,--no-undefined -Wl,-z,noexecstack -Qunused-arguments -Wl,-z,relro -Wl,-z,now -shared -Wl,-soname,libopencv341.so -o ........\build\intermediates\cmake\debug\obj\arm64-v8a\libopencv341.so CMakeFiles/opencv341.dir/src/main/cpp/DetectionBasedTracker_jni.cpp.o -landroid -llog ../../../../src/main/jniLibs/arm64-v8a/libopencv_java3.so ../../../../src/main/jniLibs/arm64-v8a/libopencv_core.a ../../../../src/main/jniLibs/arm64-v8a/libopencv_highgui.a ../../../../src/main/jniLibs/arm64-v8a/libopencv_imgcodecs.a ../../../../src/main/jniLibs/arm64-v8a/libopencv_imgproc.a ../../../../src/main/jniLibs/arm64-v8a/libopencv_objdetect.a -llog -latomic -lm "H:/Android/sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/libs/arm64-v8a/libc++_static.a" "H:/Android/sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/libs/arm64-v8a/libc++abi.a" && cd ."
CMakeFiles/opencv341.dir/src/main/cpp/DetectionBasedTracker_jni.cpp.o: In function CascadeDetectorAdapter::detect(cv::Mat const&, std::__ndk1::vector<cv::Rect_<int>, std::__ndk1::allocator<cv::Rect_<int> > >&)': H:\opencv\OpenCV4Android-master\app\src\main\cpp/DetectionBasedTracker_jni.cpp:43: undefined reference to cv::CascadeClassifier::detectMultiScale(cv::_InputArray const&, std::ndk1::vector<cv::Rect, std::ndk1::allocator<cv::Rect > >&, double, int, int, cv::Size, cv::Size)'
clang++.exe: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.