include verbatim or (escape %D%) possible?

[Thomas Martitz]

Hello,

my name is Thomas Martitz and I'd say quite knowledgeable with automake. 
However I've hit a road block that I'm unable to resolve. I'm also new 
to this list, so please bear with me.

I'm trying to port a project to non-recursive automake following[1]. I 
have come across a problem with this specific project. It uses 
convinience mk that are included by various Makefile.ams. For example, 
one of those convinience .mk files fills EXTRA_DIST with files that are 
expected in the directory of the Makefile.am. Below is a very simplified 
example of that project.

$ cat build/vars.mk
EXTRA_DIST=README COPYING

$ cat plugin1/Makefile.am
include $(top_srcdir)/build/vars.mk
$ ls plugin1/{README,COPYING}
plugin1/README plugin1/COPYING

$ cat Makefile.am
SUBDIRS = plugin1

Now, the problem comes when I try to port that Makefile.am to be 
included by the top-level Makefile.am
$ cat Makefile.am
EXTRA_DIST=
include plugin1/Makefile.am

$ cat build/vars.mk
EXTRA_DIST+=README COPYING

The problem: README and COPYING are now assumed to be in the root 
directory (which is understandable, given vars.mk now is indirectly 
included by top-level Makefile.am).

I tried to use %reldir% / %D%:
$ cat build/vars.mk
EXTRA_DIST+=%D%/README %D%7COPYING

But the effect is that README and COPYING are assumed to be in the 
*build* directory. I guess this is because %D% is expanded to the dir of 
the actual fragment file where it's used in.

So what I'm asking is: Can I somehow raw/verbatim include into 
plugin1/Makefile.am so that %D% refers to plugin1? Or is there some way 
to escape %D% once? Or is there another way to have README refer to the 
plugin1/README file by using the convinience .mk file?

Please help me.

Best regards
Thomas Martitz

[1]: http://karelzak.blogspot.de/2013/02/non-recursive-automake.html