RFR: 8241476: Linux build warning issued on updated compilers (Ubuntu 18.04.4 / 20.04)

[Thiago Milczarek Sayao]

Simple fix to remove annoying warnings.

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Commit messages:
 - Remove build warning
 - 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/150/files
 Webrev: https://webrevs.openjdk.java.net/jfx/150/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8241476
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/150.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/150/head:pull/150

PR: https://git.openjdk.java.net/jfx/pull/150