raidstart fails if the first disk of an array is unusable

  Hi. I couldn't find out who currently maintains raidtools, hopefully
this patch will find it's way to him/her via this list.

  Following a Debian bug report about raidtools' strange behaviour,
Pontus Fuchs found and fixed the cause for a problem that you possibly
have experienced: raidstart won't start an array if it can't read the
superblock from the disk that is marked first in raidtab.

  

  (Please CC me, I'm not on the list)