You might also want to look at this thread which deals with a similar problem for "libpq.so.2".
https://openacs.org/forums/message-view?message_id=138993
Note that the more recent versions of nspostgres.so use:
AOLSERVER=/path/to/aolserver
instead of:
INST=/path/to/aolserver
see: https://openacs.org/doc/current/aolserver4.html