Squashed commit of the following:

Squashed commit of the following:

commit e1ecf76585bef2eb87995f7a7f92cc12003a6f70
Author: Alan Mackenzie <acm@muc.de>
Date:   Tue Nov 24 16:50:09 2015 +0000

    Byte compile: minor amendments.

    * lisp/emacs-lisp/bytecomp.el (byte-compile-initial-macro-environment):
    add a comment to explain the binding of variables around a subsidiary
    compilation.
    (byte-compile-new-defuns): Amend the doc string.

commit c537bfed1dda1593d218956ff00c6105a3ff0316
Author: Alan Mackenzie <acm@muc.de>
Date:   Sat Nov 21 18:43:57 2015 +0000

    Byte compiler: fix spurious warnings "might not be defined at runtime".

    Also initialize byte-compile-noruntime-functions between runs.

    * lisp/emacs-lisp/bytecomp.el (byte-compile-new-defuns): New variable.
    (byte-compile-initial-macro-environment): For eval-when-compile: bind
    byte-compile-unresolved-functions and byte-compile-new-defuns around
    byte-compile-top-level, to prevent spurious entries being made.
    (byte-compile-warn-about-unresolved-functions): Check whether function is
    in byte-compile-new-defuns before emitting a warning about it.
    (byte-compile-from-buffer): Initialize new variable and
    byte-compile-noruntime-functions to nil.
    (byte-compile-file-form-require): record all new functions defined by a
    `require' in byte-compile-new-defuns.
    (byte-compile-file-form-defmumble): record the new alias in
    byte-compile-new-defuns.