Add check to see if we have root. Required for sas3ircu binary to work.

[rudybroersma]

I would like to request this merge to implement a check for root access with this wrapper script.
We use the script solo (as a standalone check) and it give misleading output without root access:

Without root:
$ /usr/bin/check_sas3ircu
-- Controller informations --
-- ID | Model

-- Arrays informations --
-- ID | Type | Size | Status

-- Disks informations
-- ID | Model | Status

$ /usr/bin/check_sas3ircu --nagios
RAID OK - Arrays: OK:0 Bad:0 - Disks: OK:0 Bad:0

$ echo $?
0

As you can see, no controller details, but the check returns exit 0. Also, Arrays and disks are both 0. A quick and easy fix is to add a check for root access.