* aports: unicsy-demo: pure Python program should have noarch set
Per https://wiki.alpinelinux.org/wiki/APKBUILD_examples:Python#arch,
pure Python programs should be marked as noarch in the APKBUILD instead
of all.
* aports: sdl_net: fix build on aarch64
The version of config.guess and config.sub predate aarch64, so
./configure errors out with instructions to update them.
Add a prepare section in APKBUILD to do this.
* aports: sdl_net+chocolate-doom: pass CHOST and CBUILD to configure
Other Alpine packages pass these options in to aid cross compling; for
example, the template APKBUILD from
https://github.com/alpinelinux/abuild/blob/master/newapkbuild.in#L43
uses them. Add them to chocolate-doom and sdl_net.
