Splits AnomalyTracker into two files

Splits out DurationAnomalyTracker-specific functions into their own
subclass.

Test: the unit tests and CTS tests
Change-Id: Id6eb74d232b4a9c3a932d805d1ba3f0ba43a88b1
diff --git a/cmds/statsd/Android.mk b/cmds/statsd/Android.mk
index f98ee3d..c392540 100644
--- a/cmds/statsd/Android.mk
+++ b/cmds/statsd/Android.mk
@@ -22,6 +22,7 @@
     src/atoms.proto \
     src/anomaly/AnomalyMonitor.cpp \
     src/anomaly/AnomalyTracker.cpp \
+    src/anomaly/DurationAnomalyTracker.cpp \
     src/condition/CombinationConditionTracker.cpp \
     src/condition/condition_util.cpp \
     src/condition/SimpleConditionTracker.cpp \