First step of making possibility to have offline snapshots of
'termux-packages' repo. Useful for making full repo snapshots.
That will allow to preinstall tools like Cmake, Go, Meson to
directory stored within packages tree and will not be wiped when
using ./clean.sh.
Next steps will also implement offlining of the package sources
and NDK standalone toolchain.
Leonid Pliushch
Fredrik Fornwall
Henrik Grimler