Capture and check top level wvtest watch messages

Capture and check top level wvtest watch messages

During wvtest watch, report top level protocol messages to stderr so
that they can be safely captured for examination by report.  Continue
printing those message to stdout too, so that "wvtest watch
... 2>test-top.log" will still display them.

Adjust "make check" to include the top level messages when looking for
failures.  Otherwise a non-zero exit status from a t/test-*.sh test that
produced no wvtest failure output of its own was just ignored.  This can
be demonstrated by adding an "exit 1" to the top of an existing test and
running "make -j check".

Thanks to Greg Troxel for reporting the problem.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>