bug#26559: [PATCH] build: emacs: Install only a subset of files.

[Arun Isaac <arunisaac@systemreboot.net>]

In the new patchset, I have cleaned up and removed some of the regexps,
as you suggested. I have also rewritten the logic using `find-files'
rather than with `ftw'.

> Note, however, that 'move-doc' procedure should be adjusted to find
> info in "doc" subdir (for "doc/*.info$" regex).

I don't think the `move-doc' phase needs to be changed. It finds .info
files with `find-files' which is recursive.

> It doesn't look right that these regexps are duplicated in 2 places.
> I'm not very familiar with build systems, but what if the
> 'include'/'exclude' arguments of 'install' procedure would simply be
> empty lists?  I think it wouldn't do harm if you leave these regexps
> only in 'emacs-build' procedure or would it?

I am not too familiar with build systems, but I think the
include/exclude arguments need to be duplicated in two places. For
example, look at arguments #:strip-flags and #:strip-directories in the
`strip' phase of the gnu-build-system. Even there, the default values of
the arguments are repeated in two places.

> I think it would be too much work.  I quickly looked at the emacs
> packages, and I believe that only slime, auctex and yasnippet need to be
> adjusted to include non-standard files.  Of course, there may be other
> packages that I'm not aware of, but they can be fixed later.

I've provided patches for emacs-slime and emacs-auctex packages as
well. I believe I got all the required files, but please check.

As it stands, emacs-yasnippet does not seem to need any changes. But, I
think the package is already broken. It needs a snippets directory
pulled from a git submodule. And, even the current package does not pull
this submodule. So, I believe the yasnippet package is already
broken. But, I don't use yasnippet, and I'm not too sure.