Framework/base: Added synchronization block to avoid race condition

Fix for the synchronization issue leading to access of an array
Index out of bounds. Issue occurs due to race condition between
removing the activities of a crashed process from history stack
and resuming a separate activity.

Change-Id: I14bb5834e778c15b674248e46fe93b0ce9f37967
remove leak WaitResult List in startActivityMayWait

Change-Id: If169ef4474a6a38eb2957c806c6e7f8f7ce67783
Signed-off-by: Young-ho Cha <ganadist@gmail.com>