Revert "Add macro seq-setq."

This reverts commit a8a3fd8f8e27089ac46bf98e534529ff03f679a5.

The same patch was applied twice.  Remove the second instance.

doc/lispref/sequences.texi

@@ -1128,23 +1128,6 @@ assigned to variables as if by @code{setq} instead of as in a
 @end example
 @end defmac
 
-@defmac seq-setq var-sequence val-sequence
-@cindex sequence destructuring
-  This macro works similarly to @code{seq-let}, except that values are
-assigned to variables as if by @code{setq} instead of as in a
-@code{let} binding.
-
-@example
-@group
-(let ((a nil)
-      (b nil))
-  (seq-setq (_ a _ b) '(1 2 3 4))
-  (list a b))
-@result{} (2 4)
-@end group
-@end example
-@end defmac
-
 @defun seq-random-elt sequence
   This function returns an element of @var{sequence} taken at random.
 

test/lisp/emacs-lisp/seq-tests.el

@@ -407,30 +407,6 @@ Evaluate BODY for each created sequence.
     (should (null b))
     (should (null c))))
 
-(ert-deftest test-seq-setq ()
-  (with-test-sequences (seq '(1 2 3 4))
-    (let (a b c d e)
-      (seq-setq (a b c d e) seq)
-      (should (= a 1))
-      (should (= b 2))
-      (should (= c 3))
-      (should (= d 4))
-      (should (null e)))
-    (let (a b others)
-      (seq-setq (a b &rest others) seq)
-      (should (= a 1))
-      (should (= b 2))
-      (should (same-contents-p others (seq-drop seq 2)))))
-  (let ((a)
-        (seq '(1 (2 (3 (4))))))
-    (seq-setq (_ (_ (_ (a)))) seq)
-    (should (= a 4)))
-  (let (seq a b c)
-    (seq-setq (a b c) seq)
-    (should (null a))
-    (should (null b))
-    (should (null c))))
-
 (ert-deftest test-seq-min-max ()
   (with-test-sequences (seq '(4 5 3 2 0 4))
     (should (= (seq-min seq) 0))