Remove unneeded entry in org-babel-tangle-lang-exts
Remove unneeded entry in org-babel-tangle-lang-exts

Also the source of a regression (causing void-variable
org-babel-tangle-lang-exts errors).

Fixes #4970
Closes #4971

hlissner/.emacs.d,hlissner/doom-emacs,hlissner/doom-emacs,hlissner/.emacs.d,hlissner/doom-emacs,hlissner/.emacs.d,hlissner/.emacs.d,hlissner/doom-emacs,hlissner/.emacs.d,hlissner/.emacs.d,hlissner/doom-emacs,hlissner/.emacs.d,hlissner/doom-emacs,hlissner/.emacs.d,hlissner/doom-emacs