Ignore duplicated chisels
Ignore duplicated chisels

This will make sysdig ignore chisels with the same name as one
already added to the list.

This currently follows the follow priority on path: . -> ~/.chisels ->
/usr/share/sysdig/chisels (this last one depends on
MAKE_INSTALL_PREFIX).
The order is the same set for paths when libsinsp is initialized.

angeloc/sysdig,angeloc/sysdig,angeloc/sysdig,angeloc/sysdig,angeloc/sysdig