ox-beamer: Fix target export

* lisp/ox-beamer.el (beamer): Let "latex" export-back-end handle
  targets.

lisp/ox-beamer.el

@@ -260,7 +260,6 @@ Return overlay specification, as a string, or nil."
 		     (link . org-beamer-link)
 		     (plain-list . org-beamer-plain-list)
 		     (radio-target . org-beamer-radio-target)
-		     (target . org-beamer-target)
 		     (template . org-beamer-template)))
 
 
@@ -780,15 +779,6 @@ contextual information."
 	  text))
 
 
-;;;; Target
-
-(defun org-beamer-target (target _contents info)
-  "Transcode a TARGET object into Beamer code.
-CONTENTS is nil.  INFO is a plist holding contextual
-information."
-  (format "\\label{%s}" (org-export-get-reference target info)))
-
-
 ;;;; Template
 ;;
 ;; Template used is similar to the one used in `latex' back-end,