`strncpy` is deprecated for use on NUL-terminated destination strings [1].
We should prefer more robust and less ambiguous string interfaces.
Both `policy->last_governor` and `default_governor` are expected to be
NUL-terminated which is shown by their heavy usage with other string
apis like `strcmp`.
A suitable replacement is `strscpy` [2] due to the fact that it guarantees
NUL-termination on the destination buffer.