[jfx11u] RFR: 8293375: add_definitions USE_SYSTEM_MALLOC when USE_SYSTEM_MALLOC is ON

Sat Feb 11 14:18:07 UTC 2023

Clean backport. Tested in connection with 4 other WebKit fixes in the `test-kcr-11.0.19` branch, including a successful CI build. I also verfied that the native WebKit code is identical to mainline jfx after applying all patches (excluding a couple of copyright years).

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Commit messages:
 - 8293375: add_definitions USE_SYSTEM_MALLOC when USE_SYSTEM_MALLOC is ON

Changes: https://git.openjdk.org/jfx11u/pull/129/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx11u&pr=129&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293375
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jfx11u/pull/129.diff
  Fetch: git fetch https://git.openjdk.org/jfx11u pull/129/head:pull/129

PR: https://git.openjdk.org/jfx11u/pull/129