Adjust function definitions in if_pfsync.c to avoid clang 15 warnings
With clang 15, the following -Werror warnings are produced:
sys/netpfil/pf/if_pfsync.c:2439:21: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes] pfsync_pointers_init() ^ void sys/netpfil/pf/if_pfsync.c:2453:23: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes] pfsync_pointers_uninit() ^ void sys/netpfil/pf/if_pfsync.c:2503:12: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes] pfsync_init() ^ void sys/netpfil/pf/if_pfsync.c:2524:14: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes] pfsync_uninit() ^ void
This is because pfsync_pointers_init(), pfsync_pointers_uninit(),
pfsync_init(), and pfsync_uninit() are declared with (void) argument
lists, but defined with empty argument lists. Make the definitions match
the declarations.
MFC after: 3 days