temp/qemu: Package for x86 and x86_64 only (!312)

This is package is meant to work around the qemu static deadlock while
cross-compiling.

- pmbootstrap binfmt_misc chroots on arm hosts are untested
- upstream jemalloc package has armv7 disabled. It is uncertain what is
  wrong with jemalloc for armv7.

For these reasons, disable the arm packages.

temp/qemu/APKBUILD

@@ -5,7 +5,7 @@ pkgver=3.1.0
 pkgrel=3
 pkgdesc="QEMU is a generic machine emulator and virtualizer"
 url="http://qemu.org/"
-arch="all"
+arch="x86 x86_64"
 license="GPL-2.0 LGPL-2"
 makedepends="
 	alsa-lib-dev