dashboard: fix build

Tests (and binaries) panicked before this.

Change-Id: If984e9e30016d403af2a94971fc4a419a269b73a
Reviewed-on: https://go-review.googlesource.com/46510
Reviewed-by: Brad Fitzpatrick <[email protected]>

Author: bradfitz

dashboard/builders.go

@@ -913,7 +913,7 @@ func init() {
 	addBuilder(BuildConfig{
 		Name:          "linux-arm-nativemake",
 		Notes:         "runs make.bash on real ARM hardware, but does not run tests",
-		HostType:      "host-linux-arm",
+		HostType:      "host-linux-arm-scaleway",
 		StopAfterMake: true,
 	})
 	addBuilder(BuildConfig{