In DG/UX R4.20MU04 we find:

Inside /usr/lib two libelf libraries

/usr/lib/libelf.a
/usr/lib/libelf.so

as symbolic links:

libelf.a -> /usr/sde/.elink./dg/usr/lib/libelf.a
libelf.so -> /usr/sde/.elink./dg/usr/lib/libelf.so

Aka these are inside /usr/sde/ix86dgux/usr/lib/ 

/usr/sde/ix86dgux/usr/lib/libelf.a
/usr/sde/ix86dgux/usr/lib/libelf.so

Either upgrade to MU07 or install the elf library
files in your older DG/UX systems 

(get the file libelf.tar from that same directory)

cp libelf.a   /usr/sde/ix86dgux/usr/lib/
cp libelf.so  /usr/sde/ix86dgux/usr/lib/

and then make symbolic links as: 

cd /usr/lib

ln -s /usr/sde/.elink./dg/usr/lib/libelf.a libelf.a
ln -s /usr/sde/.elink./dg/usr/lib/libelf.so libelf.so


Takis
Cambridge April 7 2002