Merge branch 'aarch64'
kernel: remove lots of modules which aren't needed (esp multimedia drivers)
radvd: updated to upstream version 2.21
mgetty: fix aarch64 build
build_all_archs: add aarch64
strace: disbale mpers required for aarch64 toolchain.
libgpgerror: add aarch64 toolchain
accel-ppp: requires libucontext (at least for aarch64 and shouldn't harm other toolchains...?)