[jdk11u-dev] RFR: 8284772: 8u GHA: Use GCC Major Version Dependencies Only

[Andrew John Hughes]

GHA is currently broken in 11u-dev as the referenced Ubuntu gcc package, `10.3.0-1ubuntu1~20.04`, is no longer available.

Rather than bumping this yet again, this PR suggests dropping the specific version as we did some time ago in 8u. The requirement still specifies a specific major version of GCC. It just means the dependency isn't broken every time Ubuntu bumps to a new minor release or even just makes a minor change to the package alone.

Note that the current setup does not guarantee sticking with an exact version of GCC anyway, because - as seen by the current GHA breakage - older versions get removed from the package repository. All we get from this exact version requirement is sporadic breakage. If we truly want a static version of GCC, we need to provide our own as we do with the JDK.

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Commit messages:
 - Backport 62defc3dfc4b9ba5adfe3189f34fe8b3f59b94a0

Changes: https://git.openjdk.org/jdk11u-dev/pull/2087/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2087&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8284772
  Stats: 5 lines in 1 file changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2087.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2087/head:pull/2087

PR: https://git.openjdk.org/jdk11u-dev/pull/2087