[O] [BUG] ob-perl variable handling broken

[Rick Frankel]

The commit ca125b82b changed a lot of the variable handling in
ob-perl, and it now will not accept tables as input. Below is an org
doc with an example, the error message and a backtrace.

rick
-----

* Can't use table as input
#+name: t1
| 1 | 
#+begin_src perl :var t=t1 :results value
  $t
#+end_src  
** Error
mapconcat: Wrong type argument: sequencep, 1
#+begin_example
  org-babel-perl--var-to-perl(1)
  mapconcat(org-babel-perl--var-to-perl (1) "")
  org-babel-perl--var-to-perl((1))
  mapconcat(org-babel-perl--var-to-perl ((1)) "")
  org-babel-perl--var-to-perl(((1)))
  org-babel-perl--var-to-perl(((1)) t)
  #[(pair) "address@hidden"\207" [pair org-babel-perl--var-to-perl] 3]((t (1)))
  mapcar(#[(pair) "address@hidden"\207" [pair org-babel-perl--var-to-perl] 3] 
((t (1))))
  org-babel-variable-assignments:perl(((:comments . "") (:shebang . "") (:cache 
. "no") (:padline . "") (:noweb . "no") (:tangle . "no") (:exports . "results") 
(:results . "replace value") (:var t (1)) (:session . "none") (:hlines . "no") 
(:padnewline . "yes") (:result-type . value) (:result-params "value" "replace") 
(:rowname-names) (:colname-names)))
  org-babel-execute:perl("$t" ((:comments . "") (:shebang . "") (:cache . "no") 
(:padline . "") (:noweb . "no") (:tangle . "no") (:exports . "results") 
(:results . "replace value") (:var t (1)) (:session . "none") (:hlines . "no") 
(:padnewline . "yes") (:result-type . value) (:result-params "value" "replace") 
(:rowname-names) (:colname-names)))
  org-babel-execute-src-block(nil ("perl" "$t" ((:comments . "") (:shebang . 
"") (:cache . "no") (:padline . "") (:noweb . "no") (:tangle . "no") (:exports 
. "results") (:results . "replace value") (:var t (1)) (:session . "none") 
(:hlines . "no") (:padnewline . "yes") (:result-type . value) (:result-params 
"value" "replace") (:rowname-names) (:colname-names)) "" nil 0))
  org-babel-execute-src-block-maybe()
  org-babel-execute-maybe()
  org-babel-execute-safely-maybe()
  run-hook-with-args-until-success(org-babel-execute-safely-maybe)
  org-ctrl-c-ctrl-c(nil)
  call-interactively(org-ctrl-c-ctrl-c nil nil)
  command-execute(org-ctrl-c-ctrl-c)
#+end_example