find: handle leading -- argument

function                                             old     new   delta
find_main                                            464     478     +14

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/findutils/find.c b/findutils/find.c
index 6407c6c..06ad1b3 100644
--- a/findutils/find.c
+++ b/findutils/find.c
@@ -1467,6 +1467,12 @@
 			break;
 		if (!saved[1])
 			break; /* it is "-" */
+		if (saved[1] == '-' && !saved[2]) {
+			/* it is "--" */
+			/* Try: find -- /dev/null */
+			saved = *++past_HLP;
+			break;
+		}
 		if ((saved+1)[strspn(saved+1, "HLP")] != '\0')
 			break;
 	}