[3.11] main/xen: security fixes
main/xen: security fixes for XSA-333, XSA-334, XSA-336, XSA-337, XSA-338, XSA-339, XSA-340, XSA-342, XSA-343 and XSA-344
Fixes CVEs:
- CVE-2020-25602
- CVE-2020-25598
- CVE-2020-25604
- CVE-2020-25595
- CVE-2020-25597
- CVE-2020-25596
- CVE-2020-25603
- CVE-2020-25600
- CVE-2020-25599
- CVE-2020-25601
Backport of !12743 (merged) to 3.11-stable.