aports: clean up APKBUILD for unicsy-demo, sdl_net, and chocolate-doom (#664)

* 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.

main/chocolate-doom/APKBUILD

@@ -13,7 +13,10 @@ builddir="$srcdir/${pkgname}-${pkgver}"
 
 build(){
 	cd "$builddir"
-	./configure --prefix=/usr
+	./configure \
+		--build=$CBUILD \
+		--host=$CHOST \
+		--prefix=/usr
 	make
 }
 

main/sdl_net/APKBUILD

@@ -10,9 +10,18 @@ makedepends="sdl-dev"
 source="https://www.libsdl.org/projects/SDL_net/release/SDL_net-$pkgver.tar.gz"
 builddir="$srcdir/SDL_net-$pkgver"
 
+prepare() {
+	default_prepare
+	update_config_sub
+	update_config_guess
+}
+
 build() {
   cd $builddir
-  ./configure --prefix=/usr --disable-static
+  ./configure \
+	--build=$CBUILD \
+	--host=$CHOST \
+	--prefix=/usr --disable-static
   make
 }
 

main/unicsy-demo/APKBUILD

@@ -3,7 +3,7 @@ pkgver=0.2
 pkgrel=1
 pkgdesc="Phone hardware demo (battery status, light sensors, accelerometer, LEDs, backlights)"
 url="https://github.com/pavelmachek/unicsy_demo"
-arch="all"
+arch="noarch"
 license="GPL3"
 depends="py-gtk-dev"
 makedepends=""