fixed make test reporting success when provision fails

fixed make test reporting success when provision fails

We were getting build test 'pass' on the build farm when the provision
is failing. The cause was the use of filter pipelines in the selftest
code in the makefile. A bourne shell will by default report the error
status of the last element of the pipeline, which means when provision
failed, make thought everything had passed.

We could use the bash 'pipefail' option to fix this, but it isn't
portable, so instead I've modified the makefile to touch st/st_done
when the first element in the pipeline completes successfully. That
means we now get errors in make test, at the expense of making the
makefile even more horrible than it was.