Use github actions for CI
Use github actions for CI

Performs a cross-compile for arm32 and ppc64le, and a native build.

Signed-off-by: Joel Stanley <4816dabf8db1bc6cac35b3a24cab2ff844b5b0c7@jms.id.au>

open-power/pdbg,open-power/pdbg,open-power/pdbg