Rework test 018 slightly so that its more user friendly when it fails

018.out

@@ -0,0 +1,10 @@
+QA output created by 018
+*** init FS
+meta-data=DDEV isize=XXX agcount=N, agsize=XXX blks
+data     = bsize=XXX blocks=XXX, imaxpct=PCT
+         = sunit=XXX swidth=XXX, unwritten=X
+naming   =VERN bsize=XXX
+log      =LDEV bsize=XXX blocks=XXX
+realtime =RDEV extsz=XXX blocks=XXX, rtextents=XXX
+*** compare logprint
+*** unmount