Add support for AIX

[daltenty]

Add a basic implementation for AIX using os_uuid attribute.

[sideeffect42]

Small improvement: add -F value to the lsattr command to print only the UUID instead of cutting the 2nd field of the output.

e.g.

$ lsattr -E -l sys0 -a os_uuid -F value
027ac63b-afff-492f-8e1c-bda6ab0f9ff6

Im not a Go person, but if calling a C function is possible, there would be getosuuid().