This PR outputs binaries with BUILD_W_C=1 (#2924)
This PR outputs binaries with BUILD_W_C=1 (#2924)

When BUILD_WITH_CONTAINER=1 is set, this PR outputs all relevant binaries
for envoy. This target can be used to export the build cache, or
alternatively it may be viable to use the build cache directly in the
Istio build, linking these two repositories via a volume mount.
istio/proxy,istio/proxy,istio/proxy,istio/proxy