Avoid building jemalloc on CI

Author: Mark-Simulacrum

.github/workflows/ci.yml

@@ -67,14 +67,15 @@ jobs:
           echo -1 | sudo tee /proc/sys/kernel/perf_event_paranoid
 
       - name: Install servo dependencies
-        run: sudo apt-get install -y llvm-dev clang libx11-dev python2.7 autoconf2.13
+        run: sudo apt-get install -y llvm-dev clang libx11-dev python2.7 autoconf2.13 libjemalloc-dev
 
       - name: Build collector
         run: cargo build -p collector
 
       - name: Check benchmarks
         run: sh -x -c "ci/check-benchmarks.sh"
         env:
+          JEMALLOC_OVERRIDE: /usr/lib/x86_64-linux-gnu/libjemalloc.so
           BENCH_INCLUDE_EXCLUDE_OPTS: ${{ matrix.BENCH_INCLUDE_EXCLUDE_OPTS }}
           BUILD_KINDS: ${{ matrix.BUILD_KINDS }}
           SHELL: "/bin/bash"