hg: openjfx/11-dev/rt: 8242490: Upgrade to gcc 9.2 on Linux

[johan at lodgon.com]

Changeset: f71a4eb6506b
Author:    kcr
Date:      2020-04-20 22:57 +0000
URL:       https://hg.openjdk.java.net/openjfx/11-dev/rt/rev/f71a4eb6506b

8242490: Upgrade to gcc 9.2 on Linux
Reviewed-by: arapte, jvos

! build.properties