Turn off GOCACHE when building go am: 54b56f2259 am: 8cd85b6cf5
am: 00330e6a0c

Change-Id: Ief0caf124bc821ca6c84516af5c13ad51cb84281
diff --git a/build-prebuilts.sh b/build-prebuilts.sh
index 7dbf590..bd57af2 100755
--- a/build-prebuilts.sh
+++ b/build-prebuilts.sh
@@ -163,6 +163,7 @@
         export GOROOT_BOOTSTRAP=${TOP}/prebuilts/go/${OS}-x86
         export GOROOT_FINAL=./prebuilts/go/${OS}-x86
         export GO_TEST_TIMEOUT_SCALE=100
+        export GOCACHE=off
         ./make.bash
         rm -rf ../pkg/bootstrap
         GOROOT=$(pwd)/.. ../bin/go install -race std