net/pecl-amqp: Update to 1.9.0

Unbreak with PHP7+

While here, set LICENSE

Changes: https://pecl.php.net/package-changelog.php?package=amqp&release=1.9.0

PR: 218829
Submitted by: olevole@olevole.ru
Approved by: garga (mentor), maintainer (timeout)
Differential Revision: https://reviews.freebsd.org/D10844