errors from port make (analyzed: bug in pkg)

[Peter]

For a long time already, I get these strange messages whenever building 
a port:

pkg: Bad argument on pkg_set 2143284626

Today I looked into it, and found it is easily reproducible:

# pkg audit whatever
pkg: Bad argument on pkg_set 2143284618
0 problem(s) in the installed packages found.
#

Looking closer, I found this offending call in src/audit.c:exec_audit():

                         pkg_set(pkg, PKG_UNIQUEID, name);

This goes into libpkg/pkg.c:pkg_vset(), but there nobody is interested 
in an UNIQUEID parameter, so that the parameter does not get fetched 
from the va_list.

It does not do any harm, but it is ugly.
Please fix.