Enhancing nobase_

[Akim Demaille]

Hi autofriends!

nobase_ is really a nice feature to cope with a structured hierarchy  
of files.  But it does not work well with packages that avoid  
recursive Makefiles.  In my case for instance, my package has a  
hierarchy of files in $(top_srcdir)/include, but it has no include/ 
Makefile.am, just $(top_srcdir)/Makefile.am, so I cannot use  
nobase_include_HEADERS, I have to declare a bazillion of include  
subdirs.

It would be nice if there were a means to use nobase_, but to be able  
to declare the base.  Maybe

include_BASE = include/

or something like that.  Actually, it would leave less clutter in the  
Makefile if the include_BASE was *added* where needed, rather than  
removed for install.  Instead of

include_HEADERS = include/foo.hh include/bar.hh

it would read

base_include_HEADERS = include/
nobase_include_HEADERS = foo.hh bar.hh

and automake would generate include_HEADERS as include/foo.hh include/ 
bar.hh.