ndk编译mnn时，报错：
CMake Error: CMake was unable to find a build program corresponding to "Unix Makefiles". CMAKE_MAKE_PROGRAM is not set. You probably need to select a different build tool.
CMake Error: CMAKE_C_COMPILER not set, after EnableLanguage
CMake Error: CMAKE_CXX_COMPILER not set, after EnableLanguage
CMake Error: CMAKE_ASM_COMPILER not set, after EnableLanguage
-- Configuring incomplete, errors occurred!
make: *** No targets specified and no makefile found. Stop.
原因：
没有找到ndk，ndk路径写错了
再Ubuntu子系统里面，区分大小写，Windows盘符必须小写，
比如D盘，子系统中是：
/mnt/d/
修改./bashrc文件，
export ANDROID_NDK=/mnt/d/soft/android-ndk-r23-linux/android-ndk-r23