[jdk17u-dev] RFR: 8305721: add `make compile-commands` artifacts to .gitignore

[Joshua Cao]

Not a clean backport due since JDK17 does not have .gitignore changes from [8295884](https://bugs.openjdk.org/browse/JDK-8295884)

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Commit messages:
 - 8305721: add `make compile-commands` artifacts to .gitignore

Changes: https://git.openjdk.org/jdk17u-dev/pull/1239/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1239&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305721
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1239.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1239/head:pull/1239

PR: https://git.openjdk.org/jdk17u-dev/pull/1239