.elc format: Record lambdas' doc strings lazily, not inline

.elc format: Record lambdas' doc strings lazily, not inline

Also refactor the pertinent part of bytecomp.el.

* lisp/emacs-lisp/bytecomp.el (byte-compile-output-file-form):
Use byte-compile-output-docform for all forms, not just those
with doc strings.
(byte-compile--output-docform-recurse): New function extracted
from byte-compile-output-docform.  This function recurses on
functions contained in the constants vector.
(byte-compile-output-docform): Extract parameter DOCINDEX from
the INFO list.  Add parameter CVECINDEX, the index of the
constants vector in FORM.
(byte-compile-file-form-defmumble): Several detailed
refactorings.  Call byte-compile-output-docform with the new
interface.
(byte-compile-output-as-comment): On exit, leave point after
the inserted text.  No longer assume that the output is being
inserted at the end of the buffer.