[v18.x] build: fix incorrect g++ warning message
The warning message was inadvertently changed to a newer version of g++ than the one being checked for when a refactor PR was merged to v18.x-staging.
Refs: https://github.com/nodejs/node/pull/47667
cc @nodejs/lts
Looks like this was a regression in Node.js 18.17.0.
CI: https://ci.nodejs.org/job/node-test-pull-request/57115/
CI: https://ci.nodejs.org/job/node-test-pull-request/57120/
CI: https://ci.nodejs.org/job/node-test-pull-request/57123/
CI: https://ci.nodejs.org/job/node-test-pull-request/57124/
CI: https://ci.nodejs.org/job/node-test-pull-request/57138/
CI: https://ci.nodejs.org/job/node-test-pull-request/57139/
CI: https://ci.nodejs.org/job/node-test-pull-request/57145/
CI: https://ci.nodejs.org/job/node-test-pull-request/57166/
CI: https://ci.nodejs.org/job/node-test-pull-request/57438/
CI: https://ci.nodejs.org/job/node-test-pull-request/57461/
Landed in 4b960c3a4a23.