CLION 开发C　SDL2 项目的 CmakeList 应该怎么写链接命令

参考SDL吧规贴我现在是这么写的：
cmake_minimum_required(VERSION 3.9)
project(untitled1 C)
set(CMAKE_C_STANDARD 99)
set(SDL2_INC_DIR D:\\CObject\\library\\SDL2\\include)
set(SDL2_LIB_DIR D:\\CObject\\library\\SDL2\\lib)
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -lmingw32 -lSDL2main -mwindows ")
include_directories(${SDL2_INC_DIR})
link_directories(${SDL2_LIB_DIR})
link_libraries(SDL2)
add_executable(untitled1 main.c)
target_link_libraries(untitled1 SDL2)
。。。有没有错误啊！
但是他会报错：
总是报错呢：
D:/CObject/library/SDL2/lib/SDL2main.lib(Win32/Release/SDL_windows_main.obj):(.text[_main]+0x0): multiple definition of `main'
e:/maingw/bin/../lib/gcc/mingw32/6.3.0/../../../libmingw32.a(main.o):(.text.startup+0x0): first defined here
collect2.exe: error: ld returned 1 exit status
CMakeFiles\untitled1.dir\build.make:96: recipe for target 'untitled1.exe' failed
mingw32-make.exe[3]: *** [untitled1.exe] Error 1
mingw32-make.exe[2]: *** [CMakeFiles/untitled1.dir/all] Error 2
CMakeFiles\Makefile2:66: recipe for target 'CMakeFiles/untitled1.dir/all' failed
CMakeFiles\Makefile2:78: recipe for target 'CMakeFiles/untitled1.dir/rule' failed
mingw32-make.exe[1]: *** [CMakeFiles/untitled1.dir/rule] Error 2
Makefile:117: recipe for target 'untitled1' failed
mingw32-make.exe: *** [untitled1] Error 2