github/workflows: Split QEMU/Arm builds into separate entries.

This commit takes the QEMU/Arm CI build and test step and splits it into
three separate steps (bigendian, sabrelite, thumb), to allow them to run
in parallel.

Currently the QEMU/Arm CI build step would take up to 16 minutes, often
being the last step blocking a full test run.  With this commit, when
the steps run in parallel the time it takes to complete the QEMU/Arm
build and test procedure is cut in half - taking between 8 to 9 minutes
depending on the CI runner load.

The existing `ci_build_and_test_arm` function has been removed, in
favour of having three separate functions - one per configuration.  They
are called `ci_build_and_test_arm_bigendian`,
`ci_build_and_test_arm_sabrelite`, and `ci_build_and_test_arm_thumb`.

Signed-off-by: Alessandro Gatti <a.gatti@frob.it>

.github/workflows/ports_qemu.yml

@@ -20,13 +20,20 @@ concurrency:
 
 jobs:
   build_and_test_arm:
+    strategy:
+      fail-fast: false
+      matrix:
+        ci_func:  # names are functions in ci.sh
+          - bigendian
+          - sabrelite
+          - thumb
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
     - name: Install packages
       run: source tools/ci.sh && ci_qemu_setup_arm
-    - name: Build and run test suite
-      run: source tools/ci.sh && ci_qemu_build_arm
+    - name: Build and run test suite ci_qemu_build_arm_${{ matrix.ci_func }}
+      run: source tools/ci.sh && ci_qemu_build_arm_${{ matrix.ci_func }}
     - name: Print failures
       if: failure()
       run: tests/run-tests.py --print-failures