The "lldb start" phase often times out on the iOS builder. Increase
the timeout and see if that helps.

Change-Id: I92fd67cbfa90659600e713198d6b2c5c78dde20f
Reviewed-on: https://go-review.googlesource.com/41863Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>