gitlab-ci.yml: Add jobs to test CFI flags
QEMU has had options to enable control-flow integrity features for a few months now. Add two sets of build/check/acceptance jobs to ensure the binary produced is working fine. The two sets allow testing of x86_64 binaries for every target that is not deprecated. Signed-off-by: Daniele Buono <dbuono@linux.vnet.ibm.com>