RFR: 8241474: Build failing on Ubuntu 20.04

[Thiago Milczarek Sayao]

Small fix for building on ubuntu 20.04.

-------------

Commit messages:
 - Fix build on 20.04
 - Merge pull request #7 from openjdk/master
 - Merge pull request #6 from openjdk/master
 - Merge pull request #5 from openjdk/master
 - Merge pull request #4 from openjdk/master

Changes: https://git.openjdk.java.net/jfx/pull/149/files
 Webrev: https://webrevs.openjdk.java.net/jfx/149/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8241474
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/149.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/149/head:pull/149

PR: https://git.openjdk.java.net/jfx/pull/149