Calling other external Makefiles and outside Make systems

[John Ling]

My project, for which I use Automake, needs to build libraries from 
projects outside of itself.  I tried incorporating this outside 
project's Makefiles into my own but without success.  This is because 
they define things like CPPFLAGS and top_srcdir in their own Makefiles.  
If I try to include these into my own Makefile.am it will obviously 
conflict with what my own project needs.  If anyone knows a way around 
this let me know.

In the meantime, I think the solution is to simply call the Makefile of 
this other project and let it do the building of these libraries.  But, 
I want to do this call from inside my Makefile.am.

How do I go about specifying this target, in my Makefile.am?

i.e. I want to do something like this:

loader :
       cd $(someotherdir); \
       make -f ./Makefile.loader;
where Makefile.loader is the makefile that is specific to this other 
project.  Where do I add loader as a target?

Finally, if I do get this to work, how are dependencies handled by this 
system.  i.e. if I do a make clean will it clean even those objects 
built by Makefile.loader?

Thanks,
John Ling