* lisp/emacs-lisp/bytecomp.el: Use lexical-binding.

* lisp/emacs-lisp/bytecomp.el: Use lexical-binding.
(byte-recompile-directory): Remove unused var `bytecomp-dest'.
(byte-recompile-file): Use derived-mode-p.
(byte-compile-from-buffer): Remove arg `bytecomp-filename'.
Use byte-compile-current-file instead.
(byte-compile-file): Adjust call accordingly.
(bytecomp-outbuffer): Move declaration before first use.
(for-effect): Declare dynamic.
(byte-compile-file-form-defmumble): Use byte-compile-current-file.
(byte-compile-top-level, byte-compile-out-toplevel, byte-compile-form):
Move dyn-binding of for-effect from function argument to let binding.
(byte-compile-out-toplevel): Don't both passing for-effect to
byte-optimize-lapcode.
(byte-compile-top-level-body, byte-compile-body):
Rename for-effect -> for-effect-arg so it's lexical.
* lisp/subr.el (functionp): Remove, now that it's in src/eval.c.