xfstests: RESULTS_DIR needs to be an absolute path

xfstests: RESULTS_DIR needs to be an absolute path

Some tests 'cd <somedir>' and then direct output to $RESULT_DIR,
which fails if the current working directory is not $here.
Regardless, if an external results directory is to be used it needs
to have a full path specified and the use of $here as the base of
the results files is completely incorrect.

Hence change all the $here/$seqres* references to simply be
$seqres*, and instead encode the full path to the results in
$RESULT_DIR.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Phil White <pwhite@sgi.com>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>