Found with nodejs/node#30028

Expected: g++ 6.3.0 or clang++ 8.0.0

V8 requires C++14 support, meaning we need at least g++ 5.x everywhere.

node-test-commit-v8-linux

• infra-softlayer-ubuntu1404-x64-2: (CXX=g++, 4.9.4)
• test-nearform_intel-ubuntu1604-x64-1: (CXX=g++, 5.4.0)

node-test-commit-freebsd

• test-digitalocean-freebsd11-x64-1: (CXX=ccache c++, 6.0.0)

node-test-commit-custom-suites-freestyle

• test-rackspace-ubuntu1604-x64-1: (CXX=ccache g++, 5.4.0)

node-test-commit-arm

• test-packetnet-ubuntu1604-arm64-2: (CXX=ccache g++, 5.4.0)

node-test-commit-linux-containered

• test-joyent-ubuntu1804_sharedlibs_container-x64-4: (CXX=ccache g++, 5.4.0)
• test-digitalocean-ubuntu1804_sharedlibs_container-x64-5: (CXX=ccache g++, 5.4.0)
• test-digitalocean-ubuntu1804_sharedlibs_container-x64-10: (CXX=ccache g++, 5.4.0)
• test-digitalocean-ubuntu1804_sharedlibs_container-x64-1: (CXX=ccache g++, 5.4.0)
• test-softlayer-ubuntu1804_sharedlibs_container-x64-5: (CXX=ccache g++, 5.4.0)
• test-digitalocean-ubuntu1804_sharedlibs_container-x64-7: (CXX=ccache g++, 5.4.0)

node-test-commit-linux

• test-rackspace-debian8-x64-1: (CXX=ccache g++, 4.9.2)
• test-rackspace-ubuntu1604-x64-2: (CXX=ccache g++, 5.4.0)