Ubuntu 18.04 bionic fails to build

Ubuntu 18.04 Bionic is currently failing in buildbot.

Here are links to recent builds:

• 10.1
• 10.2
• 10.3

From these logs it appears it isn't even getting out of the cmake configure stage.

In case it helps, I've attached the CMakeOutput.log and CmakeError.log log files from a manual build of 10.1.32 I did on the buildbot builder.