ci: build.sh: Add a wrapper function over the 'codestyle' job

This helper is a shell function transcript of its original GitLab CI
counterpart.

Signed-off-by: Erik Skultety <eskultet@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

ci/build.sh

@@ -57,3 +57,11 @@ run_test() {
     test -f $GIT_ROOT/build/build.ninja || run_meson_setup
     run_cmd meson test -C build $TEST_ARGS
 }
+
+run_codestyle() {
+    BUILD_ARGS="libvirt-pot-dep"
+    TEST_ARGS="--suite syntax-check --no-rebuild --print-errorlogs"
+
+    run_build
+    run_test
+}