Do not segfault when procstat -f or procstat -v is called on a process not

owned by the current user.  If kinfo_getfile() or kinfo_getvmmap() return
NULL, simply exit, and do not try and derefernce the memory.

Reviewed by:	peter
Approved by:	peter

usr.bin/procstat/procstat_files.c

@@ -144,6 +144,8 @@ procstat_files(pid_t pid, struct kinfo_proc *kipp)
 		    "PRO", "NAME");
 
 	freep = kinfo_getfile(pid, &cnt);
+	if (freep == NULL)
+		return;
 	for (i = 0; i < cnt; i++) {
 		kif = &freep[i];
 		

usr.bin/procstat/procstat_vm.c

@@ -54,6 +54,8 @@ procstat_vm(pid_t pid, struct kinfo_proc *kipp __unused)
 		    "PRES", "REF", "SHD", "FL", "TP", "PATH");
 
 	freep = kinfo_getvmmap(pid, &cnt);
+	if (freep == NULL)
+		return;
 	for (i = 0; i < cnt; i++) {
 		kve = &freep[i];
 		printf("%5d ", pid);