Giant is no longer required by vm_waitproc() and vmspace_exitfree().

Eliminate it acquisition and release around vm_waitproc() in kern_wait().

sys/kern/kern_exit.c

@@ -690,9 +690,7 @@ kern_wait(struct thread *td, pid_t pid, int *status, int options, struct rusage
 			 * to free anything that cpu_exit couldn't
 			 * release while still running in process context.
 			 */
-			mtx_lock(&Giant);
 			vm_waitproc(p);
-			mtx_unlock(&Giant);
 #ifdef MAC
 			mac_destroy_proc(p);
 #endif

sys/vm/vm_glue.c

@@ -681,7 +681,6 @@ vm_waitproc(p)
 	struct proc *p;
 {
 
-	GIANT_REQUIRED;
 	vmspace_exitfree(p);		/* and clean-out the vmspace */
 }