Multiple DKMS kernel drivers fail to build with gcc-9 [error: ‘-mindirect-branch’ and ‘-fcf-protection’ are not compatible]

[vasilisc]

DKMSKernelVersion: 5.0.0-20-generic
Date: Mon Jul 8 13:11:52 2019
DuplicateSignature: dkms:virtualbox-dkms:6.0.8-dfsg-7:./include/linux/compiler.h:192:1: error: ‘-mindirect-branch’ and ‘-fcf-protection’ are not compatible
Package: virtualbox-dkms 6.0.8-dfsg-7
PackageVersion: 6.0.8-dfsg-7
SourcePackage: virtualbox
Title: virtualbox-dkms 6.0.8-dfsg-7: virtualbox kernel module failed to build

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# LANG=C apt-cache policy gcc
gcc:
  Installed: 4:9.1.0-1ubuntu4
  Candidate: 4:9.1.0-1ubuntu4
  Version table:
 *** 4:9.1.0-1ubuntu4 500
        500 http://archive.ubuntu.com/ubuntu eoan/main amd64 Packages
        100 /var/lib/dpkg/status
---

# LANG=C lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu Eoan Ermine (development branch)
Release: 19.10
Codename: eoan

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.