We solved this whole issue (scattered includes, etc) at one job I 
had pretty simply.

Every Makefile defined a set of standard targets, notably:

includes
includeinstall
libs
libinstall
progs
proginstall

Thinks like prog: would always be dependant on ${PROGS}, then you could
add multiple programs if needed.  

So a "make World" type thing would always just do:

	make includes
	make includeinstall
	make libs
	make libinstall
	make progs
	make proginstall

Then this whole business of:

	cd /usr/include ; make ; make install
	cd /usr/lib ; make ; make install
	cd /usr/gnu/lib ; make ; make install
	....

Gets much simpler.  You can also group related systems with a mixture of
programs and libraries (like kerberos) togather more easily and still have
global makes do the right thing.

My two bits on this...
--
Mark