libraries to LDADD & DPADD for the current library, using -L OBJDIR-of-DEPLIB
so that the current library can link with the DEPLIB library built but
not installed.
Set DEPLIBS appropriately, rather than explictly adding LDADD/DPADD
for various libraries.
Reorder library build order so that libraries that depend upon any
other library are built at the end.
Whilst this change could be done in a more generic manner (and I
intend to work on that), it does remove the need to implement
top-level build targets such as "do-lib-des" (etc).
