ARM: make CRT_LEGACY_WORKAROUND work as intended

To properly support legacy ARM shared libraries, libc.so needs
to export the symbols __dso_handle and atexit, even though
these are now supplied by the crt startup code.

This patch reshuffles the existing CRT_LEGACY_WORKAROUND
conditionally compiled code slightly so it works as the
original author likely intended.

Change-Id: Id6c0e94dc65b7928324a5f0bad7eba6eb2f464b9
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@gmail.com>

libc/stdlib/atexit.c

@@ -104,17 +104,6 @@ unlock:
 	return (ret);
 }
 
-#ifdef CRT_LEGACY_WORKAROUND
-/*
- * Register a function to be performed at exit.
- */
-int
-atexit(void (*func)(void))
-{
-	return (__cxa_atexit((void (*)(void *))func, NULL, NULL));
-}
-#endif
-
 /*
  * Call all handlers registered with __cxa_atexit() for the shared
  * object owning 'dso'.