Fix benchmarks (#358)

airspeed-velocity/asv#1389 (comment)

Author: dcherian

asv_bench/asv.conf.json

@@ -27,6 +27,11 @@
   //     "python setup.py build",
   //     "PIP_NO_BUILD_ISOLATION=false python -mpip wheel --no-deps --no-index -w {build_cache_dir} {build_dir}"
   // ],
+  //
+  "build_command": [
+    "python setup.py build",
+    "python -mpip wheel --no-deps --no-build-isolation --no-index -w {build_cache_dir} {build_dir}"
+  ],
 
   // List of branches to benchmark. If not provided, defaults to "master"
   // (for git) or "default" (for mercurial).