secp256k1_ecdsa_recoverable_signature_serialize_compact - fix API

[Thomas Kerin]

Saving this for a backwards incompatible release, but it looks like

    secp256k1_ecdsa_recoverable_signature_serialize_compact(
         resource $context, 
         resource $sig, 
         &$sigOut, 
         &$recID
    );

is wrong and should be

    secp256k1_ecdsa_recoverable_signature_serialize_compact(
         resource $context, 
         &$sigOut, 
         &$recID, 
         resource $sig
    );

[Thomas Kerin]

Issue fixed in a tagged release