Since cargo-binutils 0.3.1 the `cargo objcopy` causes a build before
copying files, this doesn't work for test-runner.
We only need the actual objcopy tool, not the cargo infra here.
Based on os.phil-opp.com ideas it includes running test framework in
qemu semihosting mode so that tests can indicate pass or fail to calling
process.
GitHub Actions are configured to run these tests and validate acceptance.
Add test-runner target to perform tests in qemu.
Add -nographic for qemu running tests.
Drop serial for qemu tests as well.
* Use rlibc for memset/memcpy
* Create linker script for raspberry pi 3
* Add aarch64 target file inspired by Robigalia
* Force bitcode embedding for LTO
Berkus Decker