Draft: patches for native cross-compilation

When combined with pmbootstrap!2474 (merged) this allows for some packages to be built with abuild and the build tooling (e.g. meson) running on the native chroot rather than through QEMU, this drastically speeds up compilation.

When cross compiling, the makedepends should be split up into makedepends_host and makedepends_build. The build dependencies are those like "meson", build tools that we want to install and run on the native chroot. The host dependencies, are libraries, headers, etc for the architecture we're targeting. This follows the same semantics as Meson.

I've adjusted pmbootstrap to support these, and fall back by installing all makedepends in both chroots (which obviously isn't ideal).

device/archived/device-alcatel-idol347-downstream/APKBUILD

@@ -3,13 +3,13 @@
 pkgname=device-alcatel-idol347-downstream
 pkgdesc="Alcatel OneTouch Idol 3 (4.7) (Downstream)"
 pkgver=1
-pkgrel=2
+pkgrel=3
 url="https://postmarketos.org"
 license="MIT"
 arch="armv7"
 options="!check !archcheck"
 depends="postmarketos-base linux-alcatel-idol347-downstream mkbootimg msm-fb-refresher"
-makedepends="devicepkg-dev"
+makedepends_build="devicepkg-dev"
 source="deviceinfo"
 
 build() {