Fix broken byte-compilation of unary comparisons

* lisp/emacs-lisp/byte-opt.el (byte-opt--nary-comparison):
Fix a typo causing miscompilation of code such as (OP X),
where OP is <, >, <=, >= or =.
* test/lisp/emacs-lisp/bytecomp-tests.el
(bytecomp-tests--test-cases): Add test case.

Reported by Richard Copley.

lisp/emacs-lisp/byte-opt.el

@@ -973,7 +973,7 @@ for speeding up processing.")
   (let ((nargs (length (cdr form))))
     (cond
      ((= nargs 1)
-      `(progn (cadr form) t))
+      `(progn ,(cadr form) t))
      ((>= nargs 3)
       ;; At least 3 arguments: transform to N-1 binary comparisons,
       ;; since those have their own byte-ops which are particularly

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

@@ -780,6 +780,11 @@ inner loops respectively."
     ;; (+ 0 -0.0) etc
     (let ((x (bytecomp-test-identity -0.0)))
       (list x (+ x) (+ 0 x) (+ x 0) (+ 1 2 -3 x) (+ 0 x 0)))
+
+    ;; Unary comparisons: keep side-effect, return t
+    (let ((x 0))
+      (list (= (setq x 1))
+            x))
     )
   "List of expressions for cross-testing interpreted and compiled code.")