Prevent recursion in resumeTopActivityLocked

The existing recursion in resumeTopActivityLocked() finally caused
a problem by attempting to pause the same activity twice. By
preventing the recursion with this change we no longer face that
problem.

Fixes bug 17260463.

Change-Id: I0954614fc1a7dc0eeeef9335c1b973a42a7fc345
1 file changed