Add forgotten expect file

hphp/test/quick/string_int_arith.php.expectf

@@ -0,0 +1,17 @@
+int(16)
+int(-16)
+int(0)
+int(0)
+int(16)
+int(16)
+HipHop Warning: Division by zero in %s on line 15
+bool(false)
+int(0)
+int(28)
+int(-4)
+float(0.75)
+int(192)
+int(28)
+int(4)
+float(1.3333333333333)
+int(192)