Nlreturn sees linter error in CGO code without such error

[risentveber]

Initial issue golangci/golangci-lint#1455

Get error

client/ton_client.go:42:124: return with no blank line before (nlreturn)
	return C.GoBytes(unsafe.Pointer(data.content), C.int(data.len))

for the file with content:

func newBytesFromTcStr(data C.tc_string_data_t) []byte {
	if data.len == 0 {
		return nil
	}

	return C.GoBytes(unsafe.Pointer(data.content), C.int(data.len))
}