[RK3399][Android7.1] 调试笔记 --- 编译出错missing and no known rule to make it

Platform: RK3399-MID
OS: Android 7.1.2
Kernel: v4.4.83

问题：

客户要求把Camera2删除掉，把Camera2目录下的Android.mk修改为Android_mk后编译出错。

编译日志：

build/core/base_rules.mk:319: warning: ignoring old commands for target `out/target/product/rk3399_mid/system/lib64/libmedia.so'
Starting build with ninja
ninja: Entering directory `.'
ninja: error: 'out/target/common/obj/APPS/Camera2_intermediates/classes.noshrob.jack', needed by 'out/target/common/obj/APPS/Camera2Tests_intermediates/jack.check.timestamp', missing and no known rule to make it
build/core/ninja.mk:148: recipe for target 'ninja_wrapper' failed
make: *** [ninja_wrapper] Error 1

#### make failed to build some targets (38 seconds) ####

解决方法：

把jni和tests目录下的的Android.mk都统一修改为Android_mk；

原理：