Remove unused function in bytecomp.el

* lisp/emacs-lisp/bytecomp.el (byte-compile-delete-first): Remove.
2 jobs for master in 31 minutes and 54 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build Images
passed #48085
build-image-inotify

00:28:52

 
  Normal
passed #48086
test-lisp-emacs-lisp-inotify

00:03:02