FS-9824 [tone2wav.c] Fix segfault on tone2wav

I checked fs_encode and saw that it terminates itself a bit differently, so I applied the same to tone2wav and the segfaults went away
Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

src/tone2wav.c

@@ -172,7 +172,8 @@ int main(int argc, char *argv[])
 
  end:
 
-	switch_core_destroy();
+	switch_safe_free(SWITCH_GLOBAL_dirs.mod_dir);
+	//switch_core_destroy();
 
 	return r;