Modify hello_cc demo with copy_bom

.github/workflows/demo_test.yml

@@ -47,8 +47,9 @@ jobs:
     - name: C++ test
       run: docker exec language_support_test bash -c "cd /root/occlum/demos/hello_cc && make;
             occlum new occlum_instance;
-            cp hello_world occlum_instance/image/bin;
-            cd occlum_instance && SGX_MODE=SIM occlum build;
+            cd occlum_instance && rm -rf image;
+            copy_bom -f ../hello.yaml --root image --include-dir /opt/occlum/etc/template;
+            SGX_MODE=SIM occlum build;
             occlum run /bin/hello_world"
 
     - name: Rust test

demos/hello_cc/README.md

@@ -24,8 +24,8 @@ Either way, the resulting `hello_world` can be found in the current directory.
 3. Run `hello_world` on Occlum
 ```
 mkdir occlum_workspace && cd occlum_workspace
-occlum init
-cp ../hello_world image/bin
+occlum init && rm -rf image
+copy_bom -f ../hello.yaml --root image --include-dir /opt/occlum/etc/template
 occlum build
 occlum run /bin/hello_world
 ```

demos/hello_cc/hello.yaml

@@ -0,0 +1,7 @@
+includes:
+  - base.yaml
+targets:
+  - target: /bin
+    copy:
+      - files:
+        - ../hello_world

tools/toolchains/glibc/build.sh

@@ -31,3 +31,7 @@ CFLAGS="-O2 -g ${EXTRA_CFLAGS}" ${SRC_DIR}/configure \
   --enable-stack-protector=strong --disable-nscd ${EXTRA_CONFIG_OPTION}
 make
 make install
+
+# prepare softlinks to enable autodep for C++
+ln -sf /usr/lib/x86_64-linux-gnu/libstdc++.so.6 /opt/occlum/glibc/lib/libstdc++.so.6
+ln -sf /lib/x86_64-linux-gnu/libgcc_s.so.1 /opt/occlum/glibc/lib/libgcc_s.so.1