tree-wide: always use TAKE_FD() when calling rearrange_stdio()

rearrange_stdio() invalidates specified fds even on failure, which means
we should always invalidate the fds we pass in no matter what. Let's
make this explicit by using TAKE_FD() for that everywhere.

Note that in many places we such invalidation doesnt get us much
behaviour-wise, since we don't use the variables anymore later. But
TAKE_FD() in a way is also documentation, it encodes explicitly that the
fds are invalidated here, so I think it's a good thing to always make
this explicit here.

src/nspawn/nspawn-setuid.c

@@ -38,9 +38,9 @@ static int spawn_getent(const char *database, const char *key, pid_t *rpid) {
         if (r == 0) {
                 char *empty_env = NULL;
 
-                safe_close(pipe_fds[0]);
+                pipe_fds[0] = safe_close(pipe_fds[0]);
 
-                if (rearrange_stdio(-1, pipe_fds[1], -1) < 0)
+                if (rearrange_stdio(-1, TAKE_FD(pipe_fds[1]), -1) < 0)
                         _exit(EXIT_FAILURE);
 
                 (void) close_all_fds(NULL, 0);