[ci] Fix build

.circleci/config.yml

@@ -84,7 +84,7 @@ jobs:
     steps:
       - checkout
       - run: apt update || true
-      - run: apt install -y wget autoconf automake libtool pkg-config ragel libfreetype6-dev libfontconfig1-dev libglib2.0-dev libcairo2-dev libicu-dev libgraphite2-dev python python-pip
+      - run: apt install -y clang wget autoconf automake libtool pkg-config ragel libfreetype6-dev libfontconfig1-dev libglib2.0-dev libcairo2-dev libicu-dev libgraphite2-dev python python-pip
       - run: pip install fonttools
       - run: wget http://download.savannah.gnu.org/releases/freetype/freetype-2.9.tar.bz2 && tar xf freetype-2.9.tar.bz2 && cd freetype-2.9 && ./autogen.sh && ./configure && make -j32 && cd ..
       - run: CFLAGS="-O3" CXXFLAGS="-O3" CC=clang CXX=clang++ ./autogen.sh --with-freetype --with-fontconfig --with-glib --with-cairo --with-icu --with-graphite2