Stop supporting wrapping the build with `make`

The build servers are no longer using this. It's hard to search for
others using it -- I've cleaned them up as I've run across them, but
we'll just have to see who breaks once this goes in.

This was the last user of makeparallel, so we can remove it.

Test: make
Test: treehugger
Change-Id: If6df3f1a67d6a6df36afaa4b07cd88a48a364fe1