• changlog
  • fix white screen cause deadlock (crash_handler.cpp)
  • add switch for open/close fixlogic

handleSignal maybe cause sig delivered deadLock,and maybe block weexCoreThread on ipc，then cause whiteScreen or other issue unless restart app

• bug
  • cause 1: sigaction handler should use async-signal-safe func
  • cause 2:other logic crash or dl.
• solution:
  • google breakPad dump crash on a new process to avoid bugs.
  • tmp solution (we use): setTimeout 1s,force exit on handleExitAlarm(if has deadLock)