fix potential memory corruption in do_output() when adding UTF-8

characters, found by valgrind


git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@2233 35c25a1d-7b9e-4130-9fde-d3aeb78583b8

src/nano.c

@@ -3643,7 +3643,7 @@ void do_output(int *kbinput, size_t kbinput_len)
 
 	/* More dangerousness fun =) */
 	current->data = charealloc(current->data,
-		current_len + key_len + 2);
+		current_len + (key_len * 2));
 
 	assert(current_x <= current_len);