ci: ignore error generated by homebrew

Author: jiegec

.circleci/config.yml

@@ -125,7 +125,7 @@ jobs:
       - run:
           name: Install pkg-config
           command: |
-            brew install pkg-config libtool autoconf automake
+            brew install pkg-config libtool autoconf automake || true
       - run:
           name: Configure
           command: |