cmake: disallow '#include "SDL.h"'

cmake/test/CMakeLists.txt

@@ -41,8 +41,6 @@ add_feature_info("TEST_FULL" TEST_FULL "Build full SDL testsuite")
 find_package(SDL3 REQUIRED CONFIG COMPONENTS Headers)
 add_library(headers_test_slash OBJECT inc_sdl_slash.c)
 target_link_libraries(headers_test_slash PRIVATE SDL3::Headers)
-add_library(headers_test_noslash OBJECT inc_sdl_noslash.c)
-target_link_libraries(headers_test_noslash PRIVATE SDL3::Headers)
 
 if(TEST_SHARED)
     find_package(SDL3 REQUIRED CONFIG COMPONENTS SDL3-shared)

cmake/test/inc_sdl_noslash.c

@@ -1,8 +0,0 @@
-#include "SDL.h"
-#include "SDL_main.h"
-
-void inc_sdl_noslash(void) {
-    SDL_SetMainReady();
-    SDL_Init(0);
-    SDL_Quit();
-}