pgbench - segmentation fault

Hi,

pgbench contrib module is doing segmentation fault on Solaris
when -d option is specified without -p option specified.

This is because the -d option dumps the connection information
and the default value of pgport variable is NULL which causes
segmentation fault on Solaris when NULL is passed to printf
function.

Attached is a trivial patch that changes the default value of pgport
to empty string. PQsetdbLogin function does not make any difference
between NULL and empty string.

Regards

Julo