Add timed versions of stack dumping functions.

Under some unknown circumstances, debuggerd could become unresponsive.
If you try and take a bugreport during this time, it will hang forever.
Adding functions that have a timeout will allow dumpstate to stop if
dumping is taking too long.

Bug: 18766581

(cherry picked from commit 5f2ff6a9)

Change-Id: I39e8e9c60209e3ef9efac795fedb8e1edce2bd3e