RFR: 8307569: Build with gcc8 is broken after JDK-8307301 [v2]

[Jie Fu]

> The fix disables expansion-to-defined warning for gcc.
> Thanks.

Jie Fu has updated the pull request incrementally with one additional commit since the last revision:

  Add comment

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13850/files
  - new: https://git.openjdk.org/jdk/pull/13850/files/99d77204..064271e7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13850&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13850&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13850.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13850/head:pull/13850

PR: https://git.openjdk.org/jdk/pull/13850