bug 1408836 - update sccache to 0.2.2 to fix a Rust caching regression from Rust 1.20. r=glandium

MozReview-Commit-ID: K7dAk6wLGl7

--HG--
extra : rebase_source : e4637944c211c6ea4bc7bbe6035d1345f3057aaf

taskcluster/scripts/misc/build-sccache.sh

@@ -1,7 +1,8 @@
 #!/bin/bash
 set -x -e -v
 
-SCCACHE_REVISION=df04fa530d6b7d79fef8c848879d47dcc4d95b32
+# 0.2.2
+SCCACHE_REVISION=f5d7bac801a32734f4bf351edd6ae9a539424839
 
 # This script is for building sccache