Make the type of the memory used by the BPF filter unsigned, so it

matches the BPF registers (which are the only thing that is assigned
to/from BPF memory). This is a pedantic change that shouldn't change
any behaviour.

PR:		115931
Submitted by:	Matthew Luckie <mjl@luckie.org.nz>
Approved by:	re (bmah)
MFC after:	3 weeks

sys/net/bpf_filter.c

@@ -186,7 +186,7 @@ bpf_filter(pc, p, wirelen, buflen)
 {
 	register u_int32_t A = 0, X = 0;
 	register bpf_u_int32 k;
-	int32_t mem[BPF_MEMWORDS];
+	u_int32_t mem[BPF_MEMWORDS];
 
 	if (pc == 0)
 		/*