laszip: add long description

[ryandesign (Ryan Carsten Schmidt)]

$ port lint laszip
--->  Verifying Portfile for laszip
Error: Missing required variable: long_description
--->  1 errors and 0 warnings found.

[Veence (Vincent)]

Well, there’s hardly anything to say beyond what’s written in the description field, that’s why I left it out.

[mf2k (Frank Schima)]

I don't like it, but some ports duplicate it in that case:

long_description   $description

[ryandesign (Ryan Carsten Schmidt)]

Some MacPorts commands print the description, some print the long_description. It's a non-optional field.

[ryandesign (Ryan Carsten Schmidt)]

​https://github.com/macports/macports-ports/pull/1489

[Veence (Vincent)]

Ok, I’ve committed a long_description field identical to description.

[ryandesign (Ryan Carsten Schmidt)]

...in [8d5b0654e976259bc43f7743d3a24e4674e17a30/macports-ports]. Remember to reference the ticket URL in the commit message so that Trac can auto-close the ticket.

This breaks my PR; I'll update it.