CPAN::Tarzip.pm: Use android-compatible flags when calling gzip

On some android devices/versions, gzip won't take compound flags ala '-dc', but it'll happily accept them separately.
(I filed similar reports for other modules using gzip, like Archive::Extract)

Also, I originally filed this in https://rt.cpan.org/Public/Bug/Display.html?id=90213 but I figured a pull request would be more welcome :D