为什么CMake检查C编译器？

cmake_minimum_required(VERSION 3.6)

set(CMAKE_SYSTEM_NAME Generic)
set(CMAKE_SYSTEM_PROCESSOR arm)

set(CMAKE_C_COMPILER "arm-none-eabi-gcc")
#set(CMAKE_CXX_COMPILER "arm-none-eabi-g++")

set(CMAKE_EXE_LINKER_FLAGS "--specs=nosys.specs" CACHE INTERNAL "")

set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

project("funambule")

list(
    APPEND src
        main.c
)

add_executable(
    funambule
    ${src}
)

当我运行cmake .. CMake绝对想检查C编译器,即使我不需要一个.我怎样才能阻止它做这个无用的检查？

-- The C compiler identification is GNU 5.4.1
-- The CXX compiler identification is GNU 5.4.0
-- Check for working C compiler: /cygdrive/c/Users/NoOne/Home/bin/arm-none-eabi-gcc
-- Check for working C compiler: /cygdrive/c/Users/NoOne/Home/bin/arm-none-eabi-gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - failed
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/CC
-- Check for working CXX compiler: /usr/bin/CC -- broken
...