dumpstate: dump CPU time consumed for each thread

This should be useful to diagnose battery drain bugs due to
accidental semi-infinite busy-loop in processes that merely
get killed by the system (e.g. IMEs).

Bug: 67330309
Fixes: 67482875
Test: Manually verified by checking 'adb bugreport report.zip'
Change-Id: I1fedaf2518dd65dac105b29a74d50b51eb633cd7