Update prebuilts to go 1.13

From https://ci.android.com/builds/submitted/5859978/darwin_mac/latest/go.zip

Test: m blueprint_tools
Change-Id: I6f37742484ee4268b6a43e4cf6d818e95f151145
diff --git a/src/make.rc b/src/make.rc
index 5f888c1..f5e57e9 100755
--- a/src/make.rc
+++ b/src/make.rc
@@ -47,6 +47,7 @@
 	shift
 }
 
+GOENV=off
 GOFLAGS=()
 GO111MODULE=()
 GOROOT = `{cd .. && pwd}
@@ -76,7 +77,7 @@
 echo 'Building Go cmd/dist using '^$GOROOT_BOOTSTRAP
 if(~ $#vflag 1)
 	echo cmd/dist
-GOROOT=$GOROOT_BOOTSTRAP GOOS='' GOARCH='' $GOROOT_BOOTSTRAP/bin/go build -o cmd/dist/dist ./cmd/dist
+GOROOT=$GOROOT_BOOTSTRAP GOOS='' GOARCH='' GO111MODULE=off $GOROOT_BOOTSTRAP/bin/go build -o cmd/dist/dist ./cmd/dist
 
 eval `{./cmd/dist/dist env -9}
 if(~ $#vflag 1)