metrics: fix potential missing string termination

metrics: fix potential missing string termination

Fixes a potential memory overrun detected by Coverity.
This overrun cannot currently happen in practice because
rte_metrics_reg_names() explicitly forces the last name
character to be a NULL terminator.

This patches uses strlcpy instead of strncpy to copy name strings.

Coverity issue: 143434
Fixes: 349950ddb9c5 ("metrics: add information metrics library")
Fixes: 710cab6f675a ("metrics: fix out of bound access")
Signed-off-by: Remy Horton <remy.horton@intel.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>