Add thread suspend histogram

Helps measure time to suspend.
Example output (maps after a few seconds):
suspend all histogram:  Sum: 2.806ms 99% C.I. 2us-1090.560us Avg: 43.843us Max: 1126us

Change-Id: I7bd9dd3b401fb3e3059e8718556d60910e541611
diff --git a/runtime/base/histogram-inl.h b/runtime/base/histogram-inl.h
index b329a31..812ed86 100644
--- a/runtime/base/histogram-inl.h
+++ b/runtime/base/histogram-inl.h
@@ -35,10 +35,13 @@
     DCHECK_GT(new_max, max_);
     GrowBuckets(new_max);
   }
-
   BucketiseValue(value);
 }
 
+template <class Value> inline void Histogram<Value>::AdjustAndAddValue(Value value) {
+  AddValue(value / kAdjust);
+}
+
 template <class Value> inline Histogram<Value>::Histogram(const char* name)
     : kAdjust(0),
       kInitialBucketCount(0),