Fix for Concurrency issue reported in 525529

List of services mainted by ActivityManager may get
updated/iterated concurrently if serviceTimeout() is
scheduled simultaneously with launch/stop of new services
for the same package.To fix the issue ,iteration of
proc.executingServices set in serviceTimeout() is synchronized
with same lock used by updating the set during
start/launch of service.

CRs-fixed: 525529

Change-Id: Ic230ad0d16e6ec64a20cf394aa1c1ce777c37a2b