Fix test of FQDN
Fix test of FQDN

We can't use `hostname --fqdn` or any other shell tool because there is
no POSIX compatible way to do this short of system calls.

Unfortunately this means the test practically reimplements the original
code, but oh well.

JamesWTruher/PowerShell-1,kmosher/PowerShell,TravisEz13/PowerShell,KarolKaczmarek/PowerShell,PaulHigin/PowerShell,bingbing8/PowerShell,bingbing8/PowerShell,bingbing8/PowerShell,bmanikm/PowerShell,KarolKaczmarek/PowerShell,daxian-dbw/PowerShell,kmosher/PowerShell,jsoref/PowerShell,KarolKaczmarek/PowerShell,bmanikm/PowerShell,PaulHigin/PowerShell,TravisEz13/PowerShell,JamesWTruher/PowerShell-1,PaulHigin/PowerShell,bmanikm/PowerShell,kmosher/PowerShell,jsoref/PowerShell,bmanikm/PowerShell,TravisEz13/PowerShell,kmosher/PowerShell,jsoref/PowerShell,JamesWTruher/PowerShell-1,bmanikm/PowerShell,bingbing8/PowerShell,JamesWTruher/PowerShell-1,TravisEz13/PowerShell,PaulHigin/PowerShell,kmosher/PowerShell,daxian-dbw/PowerShell,bingbing8/PowerShell,jsoref/PowerShell,daxian-dbw/PowerShell,jsoref/PowerShell,KarolKaczmarek/PowerShell,daxian-dbw/PowerShell,KarolKaczmarek/PowerShell