Drop the high FP state of an exiting thread in cpu_thread_exit() and

not in cpu_exit(). The latter is called after td_md.md_highfp_mtx
has been destroyed, which results in a race condition when another
thread wants to use the high FP registers on the CPU that still has
the high FP registers in question.

sys/ia64/ia64/vm_machdep.c

@@ -99,6 +99,9 @@
 void
 cpu_thread_exit(struct thread *td)
 {
+
+	/* Throw away the high FP registers. */
+	ia64_highfp_drop(td);
 }
 
 void
@@ -319,10 +322,6 @@ cpu_set_fork_handler(td, func, arg)
 void
 cpu_exit(struct thread *td)
 {
-
-	/* XXX: Should this be in cpu_thread_exit() instead? */
-	/* Throw away the high FP registers. */
-	ia64_highfp_drop(td);
 }
 
 /*