xfstests: Remove dependence of xfs_check script

Replace the usage of the script xfs_check and add the relevant code to
xfstests.

This is in preparation of the planned deprecation of xfs_check.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>

tests/xfs/085

@@ -70,7 +70,7 @@ _print_logstate
 
 # curious if FS consistent at start
 if false; then
-    if $XFS_CHECK_PROG $SCRATCH_DEV; then
+    if _xfs_check $SCRATCH_DEV; then
        echo "*** checked ok ***"
     fi
 fi