add more 2 sec.

After sending SEGV signal, but no response. Try to add 2 more
seconds. If we can not have a detailed log, we need to use
gdb/lldb to show the backtrace.

tool/lib/envutil.rb

@@ -72,7 +72,7 @@ module EnvUtil
   end
   module_function :timeout
 
-  def terminate(pid, signal = :TERM, pgroup = nil, reprieve = 1)
+  def terminate(pid, signal = :TERM, pgroup = nil, reprieve = 3)
     reprieve = apply_timeout_scale(reprieve) if reprieve
 
     signals = Array(signal).select do |sig|