unicode: build maketables during build, take 2

unicode: build maketables during build, take 2

The "all:" target is the default for running gomake
by hand, but it is not used during the build.
The build runs make install and make test.

Save the build of maketables for the test phase
so that the packages it needs will have been
installed already.

R=r, r2
CC=golang-dev
https://golang.org/cl/4121043