Fix spacemacs//helm-open-buffers-in-windows

Opening more files than available windows, showed:
Symbol’s value as variable is void: cl-return

Fix #12358

CHANGELOG.develop

@@ -1515,6 +1515,8 @@ Other:
 - Load helm before read-file-name and completing-read
   (thanks duianto and thanks Miciah for a more elegant solution)
 - Added key binding `sC` for `helm-swoop-clear-cache` (thanks to Yang Qian)
+- Fixed =spacemacs//helm-open-buffers-in-windows= when opening more files than
+  available windows (thanks to Juha Jeronen)
 **** HTML
 - Added impatient-mode under ~SPC m i~ (thanks to geo7)
 - Added =counsel-css= as an =ivy= alternative to =helm-css-scss=

layers/+completion/helm/funcs.el

@@ -569,7 +569,7 @@ to buffers)."
         (cur-win (or (winum-get-number) (winum-get-number (other-window 1))))
         (num-buffers-placed 0))
     (cl-loop for buffer in buffers do
-             (when (>= num-buffers-placed num-windows) cl-return)
+             (when (>= num-buffers-placed num-windows) (cl-return))
              (set-window-buffer (winum-get-window-by-number cur-win) buffer)
              (setq cur-win (+ 1 (mod cur-win num-windows)))
              (incf num-buffers-placed))))