For a few months now QEMU has had options to enable compiler-based
control-flow integrity if built with clang.

While this feature has a low maintenance, It's probably still better to
add tests to the CI environment to check that an update doesn't break it.

As an added benefit, this also inherently tests LTO. The patch allow
gitlab testing of:
* --enable-cfi: forward-edge cfi (function pointers)
* --enable-safe-stack: backward-edge cfi (return pointers)

My original intention was to create a single chain of
build -> check -> acceptance, with all the targets compiled by default.
Unfortunately, the resulting artifact is too big and won't be uploaded.

So I split the test in two chains, that should cover all non-deprecated
targets as of today.

I also had to add a small patch to allow a custom selection for make
parallelism. This is because the gitlab runner nodes only have ~3.5GB of
ram, and with the default parallelism (2), in some cases two ld
instances will start working on two binaries and exaust the memory.
By only forcing one make job at a time, this is avoided.

Test runs of the full pipeline are here (cfi-ci branch):
https://gitlab.com/dbuono/qemu/-/pipelines/259931154

Daniele Buono (2):
  gitlab-ci.yml: Allow custom make parallelism
  gitlab-ci.yml: Add jobs to test CFI flags

 .gitlab-ci.yml | 94 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 93 insertions(+), 1 deletion(-)

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2.30.0