CA-30393: block extauth-enable if there are duplicate hostnames in the pool
CA-30393: block extauth-enable if there are duplicate hostnames in the pool

Likewise keeps the AD machine account credentials indexed by hostname.
If the same hostname is used on two different hosts, Likewise will overwrite
the AD machine account credentials of the first host with the AD machine
account credentials of the second host, and external authentication will
fail for the first host.

Signed-off-by: Marcus Granado <376d5baee5c4fa16573fd56e7ac3b2e27505de87@eu.citrix.com>

cheng--zhang/xen-api,salvocambria/xen-api,thomassa/xen-api,rafalmiel/xen-api,djs55/xen-api,anoobs/xen-api,rafalmiel/xen-api,rafalmiel/xen-api,srowe/xen-api,salvocambria/xen-api,ravippandey/xen-api,simonjbeaumont/xen-api,euanh/xen-api,huizh/xen-api,agimofcarmen/xen-api,simonjbeaumont/xen-api,euanh/xen-api,euanh/xen-api,cheng-z/xen-api,cheng-z/xen-api,rafalmiel/xen-api,koushikcgit/xen-api,djs55/xen-api,anoobs/xen-api,robertbreker/xen-api,thomassa/xen-api,srowe/xen-api,salvocambria/xen-api,jjd27/xen-api,Frezzle/xen-api,agimofcarmen/xen-api,koushikcgit/xen-api,vasilenkomike/xen-api,vasilenkomike/xen-api,ravippandey/xen-api,cheng--zhang/xen-api,simonjbeaumont/xen-api,jjd27/xen-api,cheng--zhang/xen-api,rafalmiel/xen-api,ravippandey/xen-api,srowe/xen-api,srowe/xen-api,agimofcarmen/xen-api,anoobs/xen-api,simonjbeaumont/xen-api,vasilenkomike/xen-api,guard163/xen-api,guard163/xen-api,cheng-z/xen-api,euanh/xen-api,ravippandey/xen-api,anoobs/xen-api,koushikcgit/xen-api,simonjbeaumont/xen-api,robertbreker/xen-api,cheng-z/xen-api,ravippandey/xen-api,huizh/xen-api,Frezzle/xen-api,guard163/xen-api,cheng-z/xen-api,koushikcgit/xen-api,guard163/xen-api,salvocambria/xen-api,jjd27/xen-api,cheng--zhang/xen-api,euanh/xen-api,jjd27/xen-api,rafalmiel/xen-api,thomassa/xen-api,robertbreker/xen-api,djs55/xen-api,koushikcgit/xen-api,djs55/xen-api,Frezzle/xen-api,cheng--zhang/xen-api,agimofcarmen/xen-api,anoobs/xen-api,guard163/xen-api,agimofcarmen/xen-api,Frezzle/xen-api,robertbreker/xen-api,jjd27/xen-api,djs55/xen-api,thomassa/xen-api,anoobs/xen-api,robertbreker/xen-api,thomassa/xen-api,Frezzle/xen-api,koushikcgit/xen-api,huizh/xen-api,djs55/xen-api,srowe/xen-api,thomassa/xen-api,simonjbeaumont/xen-api,huizh/xen-api,huizh/xen-api,cheng--zhang/xen-api,jjd27/xen-api,euanh/xen-api,agimofcarmen/xen-api,vasilenkomike/xen-api,salvocambria/xen-api,huizh/xen-api,cheng--zhang/xen-api,cheng-z/xen-api,guard163/xen-api,vasilenkomike/xen-api,vasilenkomike/xen-api,ravippandey/xen-api,cheng-z/xen-api,robertbreker/xen-api,salvocambria/xen-api