Adjust ng_{name,ID}_rehash() definitions to avoid clang 15 warnings
With clang 15, the following -Werror warnings are produced:
sys/netgraph/ng_base.c:981:15: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes] ng_name_rehash() ^ void sys/netgraph/ng_base.c:1012:13: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes] ng_ID_rehash() ^ void
This is because ng_name_rehash() and ng_ID_rehash() are declared with
(void) argument lists, but defined with empty argument lists. Make the
definitions match the declarations.
MFC after: 3 days