MFH: r435731

mail/thunderbird: update to 45.8.0

Changes: https://www.mozilla.org/thunderbird/45.8.0/releasenotes/
Changes: https://hg.mozilla.org/releases/comm-esr45/shortlog
Security: 96eca031-1313-4daf-9be2-9d6e1c4f1eb5
Approved by: ports-secteam (junovitch)