Build custom libgc

.circleci/config.yml

@@ -5,7 +5,8 @@ jobs:
       - image: rust
     steps:
       - run: apt -y update --fix-missing
-      - run: apt -y install libgc-dev
+      - run: apt -y install cmake
       - checkout
+      - run: git submodule update --init --recursive
       - run: cargo build
       - run: cd examples && ./test.sh