Define SDL_PLATFORM_* macros instead of underscored ones (#8875)

test/testrelative.c

@@ -12,16 +12,16 @@
 
 /* Simple program:  Test relative mouse motion */
 
-#include <stdlib.h>
-#include <time.h>
-
 #include <SDL3/SDL_test_common.h>
 #include <SDL3/SDL_main.h>
 
-#ifdef __EMSCRIPTEN__
+#ifdef SDL_PLATFORM_EMSCRIPTEN
 #include <emscripten/emscripten.h>
 #endif
 
+#include <stdlib.h>
+#include <time.h>
+
 static SDLTest_CommonState *state;
 static int i, done;
 static float mouseX, mouseY;
@@ -77,7 +77,7 @@ static void loop(void)
 
         SDL_RenderPresent(renderer);
     }
-#ifdef __EMSCRIPTEN__
+#ifdef SDL_PLATFORM_EMSCRIPTEN
     if (done) {
         emscripten_cancel_main_loop();
     }
@@ -124,7 +124,7 @@ int main(int argc, char *argv[])
     rect.h = 10;
     /* Main render loop */
     done = 0;
-#ifdef __EMSCRIPTEN__
+#ifdef SDL_PLATFORM_EMSCRIPTEN
     emscripten_set_main_loop(loop, 0, 1);
 #else
     while (!done) {