Re: new image library "requirements"

[martin rudalics]

> Maybe it should make a human-understandable report of missing
> functionality at the very end of the configure run:

I support that.

>
> ----  WARNING ----
> The following functionalities will be missing in your compilation of
> Emacs because of missing development libraries (specify
> -without-FEATURE to omit warning about such a missing feature):
>
> jpeg: used for displaying jpeg image files
> tiff: used for displaying tiff image files
> xpm: used for displaying xpm image files and color icons
> alsa: used for playing sounds from within Emacs

Including a short description of the consequences when such a
functionality is missing.