More cleanups related to number of RAID disks
Add utility function to get RAID disk index

Yet more RAID disk number cleanup.
Fix signed vs. unsigned comparison warning
Make RAID monitor use fcd_lib_disk_index when setting disk alerts
Fix RAID monitor heuristic for variable number of RAID disks
Build HDD temp monitor command array dynamically
Remove unused fcd_lib_disk_presence function
Add per-disk hddtemp_monitor_ignore config option
More HDD temperature monitor fixes for variable RAID disks

* Don't include ignored disks in hddtemp command.

* Use fcd_lib_disk_index to determine disk index when parsing
  hddtemp output.
Use .. to indicate an ignored disk in the SMART monitor
Fix HDD temperature monitor for variable RAID disks
Fix infinite loop in HDD temp monitor introduced by last commit