TBR: Makefile tweaks to respond to Adam's comments on go/vcl/2618.
TBR: Makefile tweaks to respond to Adam's comments on go/vcl/2618.

I accidentally hit "submit" before pushing my changes in response to
Adam's comments...

Change-Id: I26d971bc708a22faf896bd1529daedaaa04be21e

viksit/chat,vanadium/chat,viksit/chat,vanadium/chat,viksit/chat,vanadium/chat,viksit/chat,viksit/chat,vanadium/chat,vanadium/chat