add libglib2.0-dev for heroku build

Author: mpromonet

.circleci/config.yml

@@ -67,7 +67,7 @@ jobs:
       - attach_workspace:
           at: /          
       - checkout
-      - run: apt-get update; apt-get install -y --no-install-recommends autoconf automake libtool git cmake make g++ xz-utils pkg-config
+      - run: apt-get update; apt-get install -y --no-install-recommends autoconf automake libtool git cmake make g++ xz-utils pkg-config libglib2.0-dev
       - run: echo 'export PATH=/depot_tools:$PATH' >> $BASH_ENV
       - run: cd ${WEBRTCROOT} && gclient sync