Added actual (unpooled) partial wakelock times.

Previously, partial wakelock times reported the blame apportioned to the
app (i.e. the times were pooled). This CL adds another field to provide
the actual time the partial wakelock was held (unpooled, irrespective of
other app's wakelock usage). Full and window wakelocks also now have the
equivalent field, but it always returns -1 (like their max and current
durations), since none of those are currently tracked. Kernel wakelocks
are unchanged.

Test: cts-tradefed run cts-dev -m CtsDumpsysHostTestCases -t android.dumpsys.cts.BatteryStatsDumpsysTest
Bug: 18998184
Change-Id: Ic4cc8c3abba9afa60902d0c8e17e11abeef52a96