Update tools/cpp/toolchain_utils.bzl to return the proper C++ toolchain
Update tools/cpp/toolchain_utils.bzl to return the proper C++ toolchain

RELNOTES: None
PiperOrigin-RevId: 198676014

dropbox/bazel,safarmer/bazel,cushon/bazel,davidzchen/bazel,twitter-forks/bazel,aehlig/bazel,dropbox/bazel,ulfjack/bazel,meteorcloudy/bazel,aehlig/bazel,werkt/bazel,dslomov/bazel,ButterflyNetwork/bazel,davidzchen/bazel,dslomov/bazel,katre/bazel,twitter-forks/bazel,dslomov/bazel-windows,katre/bazel,werkt/bazel,aehlig/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,twitter-forks/bazel,akira-baruah/bazel,akira-baruah/bazel,dslomov/bazel,akira-baruah/bazel,dslomov/bazel,davidzchen/bazel,ulfjack/bazel,dslomov/bazel,cushon/bazel,bazelbuild/bazel,twitter-forks/bazel,ulfjack/bazel,akira-baruah/bazel,safarmer/bazel,ulfjack/bazel,meteorcloudy/bazel,dropbox/bazel,dslomov/bazel-windows,dropbox/bazel,bazelbuild/bazel,perezd/bazel,meteorcloudy/bazel,twitter-forks/bazel,werkt/bazel,davidzchen/bazel,akira-baruah/bazel,katre/bazel,cushon/bazel,meteorcloudy/bazel,twitter-forks/bazel,aehlig/bazel,ButterflyNetwork/bazel,ButterflyNetwork/bazel,dslomov/bazel-windows,werkt/bazel,katre/bazel,perezd/bazel,ButterflyNetwork/bazel,cushon/bazel,bazelbuild/bazel,perezd/bazel,akira-baruah/bazel,perezd/bazel,ButterflyNetwork/bazel,werkt/bazel,perezd/bazel,safarmer/bazel,dslomov/bazel,perezd/bazel,safarmer/bazel,safarmer/bazel,aehlig/bazel,cushon/bazel,dropbox/bazel,aehlig/bazel,bazelbuild/bazel,twitter-forks/bazel,perezd/bazel,davidzchen/bazel,ulfjack/bazel,dslomov/bazel,dslomov/bazel-windows,dslomov/bazel-windows,aehlig/bazel,meteorcloudy/bazel,safarmer/bazel,cushon/bazel,davidzchen/bazel,werkt/bazel,katre/bazel,ulfjack/bazel,dslomov/bazel-windows,meteorcloudy/bazel,dropbox/bazel,katre/bazel,ulfjack/bazel,bazelbuild/bazel,meteorcloudy/bazel,davidzchen/bazel