Program & Library, dev in parallel?

[Patrick M. Rutkowski]

I asked the following question in #workingset on irc.freenode.net a
little while ago, but got no response. I was hoping you guys might
chime in. I hope you won't mind the IRC format, I just copy-pasted it,
and I wanted to get this email out quickly so I can go eat :-)

[01:53am] rutski: I've got an autotools question
[01:53am] rutski: how would one go about developing two autotools
projects in parallel
[01:54am] rutski: one being a library
[01:54am] rutski: and one being an application that consumes the code
in that library
[01:54am] rutski: the problem is that the "make install" on the
library code install things into /usr/lib and /usr/include
[01:54am] rutski: and then the "make" on the application uses the
headers that were installed in /usr/include
[01:55am] rutski: but if I edit a library header and re-run "make
install" on the lib then it reinstalls _all_ the headers
[01:55am] rutski: and then when I run "make" on the app again, I have
to rebuild practically the WHOLE ******* APP! Even if I didn't change
a thing!
[01:55am] rutski: because it thinks all the /usr/include/*.h headers are changed
[01:56am] rutski: when really they didn't, because make-install just
copied over identical headers
[01:56am] rutski: any ideas?

Many thanks,
-Patrick