In order to automate certificate issuance and renewal for Raspberry Pi
devices, we need aarch64 builds of the `sshca` tool. Using the `matrix`
feature of Jenkins pipelines lets us reuse the same stage definition for
building the client on both platforms. Unfortunately, the `matrix`
block has to encompass the server stage as well, as `matrix` cannot be
nested below `parallel`, and we don't want to build the server and
clients sequentially. This makes the code a bit less clear, as the
server and client stages are now conditional based on the matrix
intersection, but it is cleaner than duplicating the entire client
stage.
Dustin C. Hatch
5f85a5a4fe