tremplin: point dnsmasq to /run/resolv.conf

This must land after both the host and guest are updated to support
the new SetResolvConf RPC.

BUG=chromium:829192
TEST=DNS in container still works
CQ-DEPEND=CL:1249678

Change-Id: Icdcab03002e64bd956a2f29cfe24c8e06e1145cd
Reviewed-on: https://chromium-review.googlesource.com/1250543
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Stephen Barber <smbarber@chromium.org>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>
diff --git a/src/chromiumos/tremplin/main.go b/src/chromiumos/tremplin/main.go
index 00b0bb2..805efac 100644
--- a/src/chromiumos/tremplin/main.go
+++ b/src/chromiumos/tremplin/main.go
@@ -65,7 +65,8 @@
 		"managed": true,
 		"config": {
 			"ipv4.address": "%s",
-			"ipv6.address": "none"
+			"ipv6.address": "none",
+			"raw.dnsmasq": "resolv-file=/run/resolv.conf"
 		}
 	}`, subnet)), &defaultNetwork); err != nil {
 		return err