ci: build native_sim with llvm

Signed-off-by: Anas Nashif <[email protected]>

Author: nashif

.github/workflows/twister.yaml

@@ -135,7 +135,7 @@ jobs:
         run: |
           export ZEPHYR_BASE=${PWD}
           export ZEPHYR_TOOLCHAIN_VARIANT=zephyr
-          ./scripts/twister -G --subset ${{matrix.subset}}/${{ strategy.job-total }} ${TWISTER_COMMON} ${PUSH_OPTIONS}
+          ./scripts/twister -G --force-platform-toolchain native_sim/native:llvm --subset ${{matrix.subset}}/${{ strategy.job-total }} ${TWISTER_COMMON} ${PUSH_OPTIONS}
           if [ "${{matrix.subset}}" = "1" ]; then
             ./scripts/zephyr_module.py --twister-out module_tests.args
             if [ -s module_tests.args ]; then
@@ -151,11 +151,11 @@ jobs:
           export ZEPHYR_BASE=${PWD}
           export ZEPHYR_TOOLCHAIN_VARIANT=zephyr
           python3 ./scripts/ci/test_plan.py -c origin/${BASE_REF}.. --pull-request --no-detailed-test-id
-          ./scripts/twister --subset ${{matrix.subset}}/${{ strategy.job-total }} --load-tests testplan.json ${TWISTER_COMMON} ${PR_OPTIONS}
+          ./scripts/twister --force-platform-toolchain native_sim/native:llvm --subset ${{matrix.subset}}/${{ strategy.job-total }} --load-tests testplan.json ${TWISTER_COMMON} ${PR_OPTIONS}
           if [ "${{matrix.subset}}" = "1" -a ${{needs.twister-build-prep.outputs.fullrun}} = 'True' ]; then
             ./scripts/zephyr_module.py --twister-out module_tests.args
             if [ -s module_tests.args ]; then
-              ./scripts/twister +module_tests.args --outdir module_tests ${TWISTER_COMMON} ${PR_OPTIONS}
+            ./scripts/twister +module_tests.args --force-platform-toolchain native_sim/native:llvm --outdir module_tests ${TWISTER_COMMON} ${PR_OPTIONS}
             fi
           fi