use Modern::Perl;

while (<DATA>) {
    my @record = split;
    if ($record[1]=~s/-$//) {
        while (<DATA>) {
            my ($continuation) = split;
            $record[1] .= $continuation;
            last unless $record[1]=~s/-$//;
        }
    }
    say join ' ', @record;
}

__DATA__
A00002   \\a00002\c$    2   WinNT   NTFS  Yes 73,626MB  42.5
A00003   /            1     Linux86 EXT3  No  38,289MB  29.8
A00004
A00004   \Sys-       1     WinNT    VSS  Yes  0 KB     0.0
         temState\-
         NULL\Syst-
         em
A00005   /xyz           4     Linux86 EXT2  No  12,345MB  30