alsapid: dont treat ENOENT on unlink as error

If handle was created but its name was not set, then symlink will not exist.
aconnect behaves like this.

alsapid/lib.c

@@ -60,7 +60,7 @@ static void destroy_symlink(int alsa_client_id)
   alsapid_compose_src_link(alsa_client_id, src);
 
   //printf("'%s'\n", src);
-  if (unlink(src) != 0)
+  if (unlink(src) != 0 && errno != ENOENT)
   {
     fprintf(stderr, "unlink(\"%s\") failed with %d (%s)", src, errno, strerror(errno));
   }