xenstored has had a testsuite for some time. This splits the test

xenstored has had a testsuite for some time.  This splits the test
targets into "make -s check" (the GNU standard) which is designed to run
in several seconds or less, with only "<dirname>:" and a seried of "."
for output, and "make fullcheck" which is more verbose and complete, and
runs in minutes.

I plan to submit a patch to plumb these tests in at the top level soon,
with the idea of having a "make -s check" which you can reasonable run
every checkin (time make check << time make), and a "make fullcheck"
which you can run after significant changes.

This patch speeds up testing by making tests one single "xs_test"
script, enhancing xs_test with a simple "expect" command.  It also only
runs the "high value" tests under "make check", and leaves the rest for
"make fullcheck".

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>