kern_sysctl: make sysctl.debug work as intended

[kaktus]

Summary

r136999 introduced SYSTCL_DEBUG but apparently "opt_sysctl.h" was never included making the option ignored.

r322954 introduced sysctl.reuse_test with OID number equal to 0, effectively shadowing the very special sysctl.debug one. Use OID_AUTO as it doesn't need any special treatment.

Test Plan

compile kernel with options SYSCTL_DEBUG and run:

sysctl sysctl.debug

observe kern.msgbuf

head/sys/kern/kern_sysctl.c

  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include "opt_capsicum.h"
 #include "opt_ddb.h"
 #include "opt_ktrace.h"
+#include "opt_sysctl.h"
 
 #include <sys/param.h>
 #include <sys/fail.h>
 #include <sys/systm.h>
 #include <sys/capsicum.h>
 #include <sys/kernel.h>
 #include <sys/limits.h>
 #include <sys/sysctl.h>

 {
         struct rm_priotracker tracker;
 
         SYSCTL_RLOCK(&tracker);
         sysctl_warn_reuse(__func__, oidp);
         SYSCTL_RUNLOCK(&tracker);
         return (0);
 }
-SYSCTL_PROC(_sysctl, 0, reuse_test, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE,
-        0, 0, sysctl_reuse_test, "-", "");
+SYSCTL_PROC(_sysctl, OID_AUTO, reuse_test,
+    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 0, sysctl_reuse_test, "-",
+    "");
 #endif
 
 void
 sysctl_register_oid(struct sysctl_oid *oidp)
 {
         struct sysctl_oid_list *parent = oidp->oid_parent;
         struct sysctl_oid *p;
         struct sysctl_oid *q;