Improve pkg_tar warning message.
Improve pkg_tar warning message.

Put the label of the target in the warning message. Without it, it's
hard to figure out which target one should fix.

Change-Id: I694737e80ed74250ea793402443eaf5d2a13d622
PiperOrigin-RevId: 166184377

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