don't enforce description_hash checking

[fiatjaf]

Although BOLT11 says "a reader MUST check" I'm not sure "reader" refers specifically to the Lightning server.

Sometimes the reader may be an application and the application may want to decode the invoice first before looking for the full description somewhere else and then proceeding to check either on its own or by calling decodepay again.

Sometimes the reader is a final payer, but there are some circumstances, like a custodial wallet provider or some other odd situations in which the Lightning server is not the final payer and thus not the "reader" that should care about this.

Sometimes the "full description" is not a UTF-8 string. In these cases they may still be checked against the description_hash but it will be impossible to pass it to lightningd.

I don't know, just think that failing when a description to be checked is not given is too brutal.

Changelog-None

[cdecker]

ACK 0ed0c13