Pointer as bool (libsdl-org#7214)

test/testsurround.c

@@ -152,7 +152,7 @@ int main(int argc, char *argv[])
 
     /* Initialize test framework */
     state = SDLTest_CommonCreateState(argv, 0);
-    if (state == NULL) {
+    if (!state) {
         return 1;
     }
 
@@ -212,7 +212,7 @@ int main(int argc, char *argv[])
         active_channel = 0;
 
         stream = SDL_OpenAudioDeviceStream(devices[i], &spec, fill_buffer, NULL);
-        if (stream == NULL) {
+        if (!stream) {
             SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_OpenAudioDeviceStream() failed: %s\n", SDL_GetError());
             continue;
         }