Issue title: Solaris 10 tar: z: unknown function modifier
 Issue body: On Solaris 10, tar fails with tar: z: unknown function modifier. The code involved is:

    _info "Extracting $localname"
    tar xzf $localname

But Solaris 10 tar does not understand modifier 'z'. As I have the gnu utilities installed, I just
replaced tar with gtar. But perhaps a better fix would be to use gzcat piped into tar.

I don't know if the tar in later versions of Solaris understand 'z' or not.




 Comments: 
 Comment 0: The `z` options is also working on my solaris machine.

Anyway, I will try to fix it later.


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