Adjust ipfw_{init,destroy}_sopt_handler() definitions to avoid clang 15 warning
With clang 15, the following -Werror warning are produced:
sys/netpfil/ipfw/ip_fw_sockopt.c:3477:23: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes] ipfw_init_sopt_handler() ^ void sys/netpfil/ipfw/ip_fw_sockopt.c:3485:26: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes] ipfw_destroy_sopt_handler() ^ void
This is because ipfw_init_sopt_handler() and ipfw_destroy_sopt_handler()
are declared with (void) argument lists, but defined with empty argument
lists. Make the definitions match the declarations.
MFC after: 3 days