Pull up following revision(s) (requested by is in ticket #1522):

etc/etc.amiga/Makefile.inc: revision 1.30
etc/etc.amiga/Makefile.inc: revision 1.31
etc/etc.amiga/Makefile.inc: revision 1.29

Provide the (small) miniroot uncompressed, so that it can be used from
an AmigaOS without additional software to install NetBSD.

Closes PR port-amiga/45443

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provide both miniroot.fs (for people wanting to install NetBSD without
more 3rdparty software than what's provided on our ISO) and .fs.tz (for
people downloading over slow links).

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Fix build; add -f flag to "rm miniroot.fs" in case of its absence.

(martin)