allow building locally as well as with docker

If docker uses the .rustwide directory, it will only be readable and
writable by root. This uses a different scratch directory so that the
.rustwide directory can be used for local builds.

Author: jyn514

docker-compose.yml

@@ -8,7 +8,7 @@ services:
             - "3000:3000"
         volumes:
             - "/var/run/docker.sock:/var/run/docker.sock"
-            - ".rustwide:/home/cratesfyi/rustwide"
+            - ".rustwide-docker:/home/cratesfyi/rustwide"
             - "cratesio-index:/opt/docsrs/prefix/crates.io-index"
         environment:
             CRATESFYI_RUSTWIDE_WORKSPACE: /home/cratesfyi/rustwide