We need run net-snmp-config-x before building perl modules. Otherwise
net-snmp-config will not be executable and net-snmp-config --libs will
fail and perl modules will be built without -lnetsnmp.

Seems also that we need build startnadall and net-snmp-create-v3-user
before building perl modules.

We could have "fixed" it by simply disabling parallel builds, but I
don't like the idea of having 1 core working and 7 cores in idle.

fixes #1263