add missing break on kern_pledge.c

[Ricardo Mestre]

Hi,

When unveil(2) was introduced one break from SYS_stat case was removed on
kern_pledge.c, this adds it back. Noticed by Coverity 1471854.

OK?

Index: kern_pledge.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_pledge.c,v
retrieving revision 1.242
diff -u -p -u -r1.242 kern_pledge.c
--- kern_pledge.c       20 Aug 2018 10:00:04 -0000      1.242
+++ kern_pledge.c       12 Sep 2018 09:46:16 -0000
@@ -623,6 +623,7 @@ pledge_namei(struct proc *p, struct name
                        } else
                                return (pledge_fail(p, error, PLEDGE_GETPW));
                }
+               break;
        case SYS_open:
                /* daemon(3) or other such functions */
                if ((ni->ni_pledge & ~(PLEDGE_RPATH | PLEDGE_WPATH)) == 0 &&