build.make: clarify usage of "make V=1"
build.make: clarify usage of "make V=1"

This may or may not work, depending on which packages have tests and
whether they contain glog.

kubernetes-csi/csi-lib-utils,kubernetes-csi/csi-driver-nfs,kubernetes-csi/csi-driver-nfs,kubernetes-csi/csi-driver-nfs,kubernetes-csi/csi-lib-utils,kubernetes-csi/csi-lib-utils,kubernetes-csi/external-attacher-csi