fix compatibility with curl-7.62

[vcunat]

curl/curl@3f3b26d6fe

Fixes #310.

[vcunat]

@geometer: no interest in similar pull requests?

[geometer]

Sorry, the project is dead. We are working on a new incarnation of FBReader/C++, but it is not open-source at the moment.

[vcunat]

Thanks for clarifying that! And thanks for FBReader :-) I hope you'll be able to open your further work, too.

[djdron]

Sorry, the project is dead. We are working on a new incarnation of FBReader/C++, but it is not open-source at the moment.

Hi! How did you close GPL'ed sources? WTF?

[vcunat]

I haven't read about re-using these sources and I'm no lawyer either, but I believe it's perfectly allowed for the copyright owner(s) to re-license sources to whatever they like. Of course, in community projects there are often too many authors to get permissions from everyone, but I don't expect that to be the case here.

From non-lawyer point of view, the fact that someone was giving away their work for free... certainly doesn't oblige them to continue doing so. And anyone can pick up this particular project and continue maintaining it (in a fork at least).