Axe KTR_ALQ_MASK now that KTR_WITNESS is off unless you hack an #ifdef

in subr_witness.c.  I did add a comment in subr_witness.c noting that
KTR_WITNESS is incompatible with KTR_ALQ.

sys/kern/kern_ktr.c

@@ -148,7 +148,6 @@ sysctl_debug_ktr_alq_enable(SYSCTL_HANDLER_ARGS)
 		    req->td->td_ucred, ALQ_DEFAULT_CMODE,
 		    sizeof(struct ktr_entry), ktr_alq_depth);
 		if (error == 0) {
-			ktr_mask &= ~KTR_ALQ_MASK;
 			ktr_alq_cnt = 0;
 			ktr_alq_failed = 0;
 			ktr_alq_enabled = 1;

sys/kern/subr_witness.c

@@ -103,6 +103,7 @@ __FBSDID("$FreeBSD$");
 
 #include <machine/stdarg.h>
 
+/* Note that these traces do not work with KTR_ALQ. */
 #if 0
 #define	KTR_WITNESS	KTR_SUBSYS
 #else

sys/sys/ktr.h

@@ -100,9 +100,6 @@
 #define KTR_COMPILE 0
 #endif	/* KTR */
 
-/* Trace classes that can not be used with KTR_ALQ */
-#define	KTR_ALQ_MASK	(KTR_WITNESS)
-
 /*
  * Version number for ktr_entry struct.  Increment this when you break binary
  * compatibility.