xfstests: introduce a common directory

xfstests: introduce a common directory

Introduce a top level common directory and move all the common.*
files into it.  Because there is now a directory named common, the
prefix can be dropped from all the files. Convert all the tests to
use this new directory for including common files.

for f in common.*; do \
	git mv `echo -n "$f " ; echo $f | sed -e 's;n\.;n/;'` \
done

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Phil White <pwhite@sgi.com>
[rjohnston@sgi.com reworked for TOT changes]
Signed-off-by: Rich Johnston <rjohnston@sgi.com>