build: break builds

I want to see the timing information in build logs,
and we can't see the logs for "ok" builds.
So make the build fail everywhere.

Will roll back immediately.

TBR=dvyukov
CC=golang-dev
https://golang.org/cl/12058046

src/run.bash

@@ -185,3 +185,5 @@ go tool api -c $GOROOT/api/go1.txt,$GOROOT/api/go1.1.txt -next $GOROOT/api/next.
 
 echo
 echo ALL TESTS PASSED
+
+exit 1