CI: build: fix use of sdk as toolchain

The toolchain included in a sdk have a different format than an external
toolchain tar.

Since sdk is a more integrated setup doesn't use and include wrapper bin
that use the external toolchain config and use an alternative and more
standard way to include all the toolchain headers.

External toolchain use wrapper.sh to append the configured include
header when each tool is called.

Fix the sdk toolchain by reverting their own sdk wrapper scripts and to
simulate an external toolchain build copying what is done in the
toolchain target makefile.

This handle compilation error and warning caused by not using fortify
header on building packages.

Fixes: 006e52545d ("CI: build: add support to fallback to sdk for external toolchain")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

.github/workflows/build.yml

@@ -266,6 +266,34 @@ jobs:
             --overwrite-config \
             --config ${{ env.TARGET }}/${{ env.SUBTARGET }}
 
+      - name: Adapt external sdk to external toolchain format
+        if: inputs.build_toolchain == false && steps.parse-toolchain.outputs.toolchain-type == 'external_sdk'
+        shell: su buildbot -c "sh -e {0}"
+        working-directory: openwrt
+        run: |
+          TOOLCHAIN_DIR=${{ env.TOOLCHAIN_FILE }}/staging_dir/$(ls ${{ env.TOOLCHAIN_FILE }}/staging_dir | grep toolchain)
+          TOOLCHAIN_BIN=$TOOLCHAIN_DIR/bin
+          OPENWRT_DIR=$(pwd)
+
+          # Find target name from toolchain info.mk
+          GNU_TARGET_NAME=$(cat $TOOLCHAIN_DIR/info.mk | grep TARGET_CROSS | sed 's/^TARGET_CROSS=\(.*\)-$/\1/')
+
+          cd $TOOLCHAIN_BIN
+
+          # Revert sdk wrapper scripts applied to all the bins
+          for app in $(find . -name "*.bin"); do
+            TARGET_APP=$(echo $app | sed 's/\.\/\.\(.*\)\.bin/\1/')
+            rm $TARGET_APP
+            mv .$TARGET_APP.bin $TARGET_APP
+          done
+
+          # Setup the wrapper script in the sdk toolchain dir simulating an external toolchain build
+          cp $OPENWRT_DIR/target/toolchain/files/wrapper.sh $GNU_TARGET_NAME-wrapper.sh
+          for app in cc gcc g++ c++ cpp ld as ; do
+            [ -f $GNU_TARGET_NAME-$app ] && mv $GNU_TARGET_NAME-$app $GNU_TARGET_NAME-$app.bin
+            ln -sf $GNU_TARGET_NAME-wrapper.sh $GNU_TARGET_NAME-$app
+          done
+
       - name: Configure external toolchain with sdk
         if: inputs.build_toolchain == false && steps.parse-toolchain.outputs.toolchain-type == 'external_sdk'
         shell: su buildbot -c "sh -e {0}"