cmake时MNN_BUILD_TOOL不生效，导致make后没有产出modelCompare.out

[lufeiabc123]

平台(linux 服务器):

Github版本:2.9.2

编译方式:

cmake .. -DMNN_BUILD_TOOL=ON make -j4

请在这里粘贴cmake参数或使用的cmake脚本路径以及完整输出
```-- The C compiler identification is GNU 9.4.0
-- The CXX compiler identification is GNU 9.4.0
-- The ASM compiler identification is GNU
-- Found assembler: /usr/bin/cc
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Use Threadpool, forbid openmp
-- >>>>>>>>>>>>>
-- MNN BUILD INFO:
--      System: Linux
--      Processor: x86_64
--      Version: 2.9.2
--      Metal: OFF
--      OpenCL: OFF
--      OpenGL: OFF
--      Vulkan: OFF
--      ARM82: OFF
--      oneDNN: OFF
--      TensorRT: OFF
--      CoreML: OFF
--      NNAPI: OFF
--      CUDA: OFF
--      OpenMP: OFF
--      BF16: OFF
--      ThreadPool: ON
--      Hidden: TRUE
--      Build Path: /opt/MNN/build_compare
--      CUDA PROFILE: OFF
-- WIN_USE_ASM: 
-- x86_64: Open SSE
-- MNN_AVX512:OFF
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE  
-- Configuring done
-- Generating done
CMake Warning:
  Manually-specified variables were not used by the project:

    MNN_BUILD_TOOL

问题

cmake的时候 MNN_BUILD_TOOL=ON不生效，导致不能生成modelCompare.out

[jxt1234]

这个测试工具删掉了，不过文档上面还有，我们先补回来吧。临时可以先切到 2.6.0 编译该工具

[jxt1234]

临时加回去了，更新代码即可

[lufeiabc123]

临时加回去了，更新代码即可 可以用了，谢谢~