I believe you want to do this:
libexecdir='${prefix}/lib'
which will carry over unexpanded to your Makefiles, where prefix is given a proper value.
That would break the configure --libexecdir option, though.
I finally get it. I think you're right, you cannot change the default values of the "standard" variables. In some ways, Autoconf assumes that one is building a standard Gnu package, with all that entails about directory stricture and names. There is some flexibility in this area, but not as much as one might like.
I think the only thing you could do is "edit" the value after AC_INIT happens, taking some care to check that the user didn't explicitly set it on the command line - I'm not sure how to do this without using internal details of the generated configure script ...
- John Burger MITRE
