Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/github.com/json-iterator/go/iter_array.go

@@ -0,0 +1,58 @@
+package jsoniter
+
+// ReadArray read array element, tells if the array has more element to read.
+func (iter *Iterator) ReadArray() (ret bool) {
+	c := iter.nextToken()
+	switch c {
+	case 'n':
+		iter.skipThreeBytes('u', 'l', 'l')
+		return false // null
+	case '[':
+		c = iter.nextToken()
+		if c != ']' {
+			iter.unreadByte()
+			return true
+		}
+		return false
+	case ']':
+		return false
+	case ',':
+		return true
+	default:
+		iter.ReportError("ReadArray", "expect [ or , or ] or n, but found "+string([]byte{c}))
+		return
+	}
+}
+
+// ReadArrayCB read array with callback
+func (iter *Iterator) ReadArrayCB(callback func(*Iterator) bool) (ret bool) {
+	c := iter.nextToken()
+	if c == '[' {
+		c = iter.nextToken()
+		if c != ']' {
+			iter.unreadByte()
+			if !callback(iter) {
+				return false
+			}
+			c = iter.nextToken()
+			for c == ',' {
+				if !callback(iter) {
+					return false
+				}
+				c = iter.nextToken()
+			}
+			if c != ']' {
+				iter.ReportError("ReadArrayCB", "expect ] in the end, but found "+string([]byte{c}))
+				return false
+			}
+			return true
+		}
+		return true
+	}
+	if c == 'n' {
+		iter.skipThreeBytes('u', 'l', 'l')
+		return true // null
+	}
+	iter.ReportError("ReadArrayCB", "expect [ or n, but found "+string([]byte{c}))
+	return false
+}