unexport proc_clear_tty

With the removal of the Solaris binary emulation the export of
proc_clear_tty became unused.
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/tty_io.c

@@ -3580,7 +3580,6 @@ void proc_clear_tty(struct task_struct *p)
 	p->signal->tty = NULL;
 	spin_unlock_irq(&p->sighand->siglock);
 }
-EXPORT_SYMBOL(proc_clear_tty);
 
 /* Called under the sighand lock */