Add an LLEXT build test

Add a GitHub workflow entry to build with LLEXT enabled, using the
Zephyr toolchain.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

.github/workflows/llext.yml

@@ -0,0 +1,41 @@
+---
+
+name: Zephyr LLEXT
+
+# 'workflow_dispatch' allows running this workflow manually from the
+# 'Actions' tab
+# yamllint disable-line rule:truthy
+on: [pull_request, workflow_dispatch]
+
+jobs:
+ build:
+ runs-on: ubuntu-22.04
+
+ strategy:
+ fail-fast: false
+ matrix:
+ platform: [mtl, lnl]
+
+ steps:
+ - name: git clone sof
+ uses: actions/checkout@v4
+ with:
+ path: ./workspace/sof
+ fetch-depth: 0 # fix git describe
+ filter: 'tree:0'
+
+ - name: west clones
+ run: pip3 install west && cd workspace/sof/ && west init -l &&
+ west update --narrow --fetch-opt=--depth=5
+
+ - name: Download docker image && ls /opt/toolchains/
+ run: cd workspace && ./sof/zephyr/docker-run.sh ls -l /opt/toolchains/
+
+ - name: llext build
+ run: |
+ cd workspace && ./sof/zephyr/docker-run.sh /bin/sh -c \
+ 'ln -s /opt/toolchains/zephyr-sdk-* ~/;
+ west build --board intel_adsp_ace15_mtpm sof/app \
+ -- -DEXTRA_CFLAGS=-Werror -DEXTRA_CXXFLAGS=-Werror \
+ -DEXTRA_AFLAGS=-Werror \
+ -DOVERLAY_CONFIG=overlays/mtl/module_overlay.conf'