Remove SDL_config.h from the public headers

The SDL headers are no longer dependent on the build configuration.

Fixes https://github.com/libsdl-org/SDL/issues/6643 and https://github.com/libsdl-org/SDL/issues/6641

test/testsensor.c

@@ -119,3 +119,5 @@ main(int argc, char **argv)
     SDL_Quit();
     return (0);
 }
+
+/* vi: set ts=4 sw=4 expandtab: */