Avoid creating temporary objects in FiterValue().

It reduces the cpu time from 1000ns to 750ns

Test: statsd test.
Change-Id: Ifa7e98e3368f8d55f85c7b09d05a6c416482981d
diff --git a/cmds/statsd/Android.mk b/cmds/statsd/Android.mk
index 740fdc0..dbcc888 100644
--- a/cmds/statsd/Android.mk
+++ b/cmds/statsd/Android.mk
@@ -239,7 +239,8 @@
                    benchmark/main.cpp \
                    benchmark/hello_world_benchmark.cpp \
                    benchmark/log_event_benchmark.cpp \
-                   benchmark/stats_write_benchmark.cpp
+                   benchmark/stats_write_benchmark.cpp \
+                   benchmark/filter_value_benchmark.cpp
 
 LOCAL_C_INCLUDES := $(statsd_common_c_includes)