Remove unused variables in statsd, and make more warnings show.

Test: statsd_test

Change-Id: I2c7b674cb615f22c5de90c2de5f2d58108ab2e7f
diff --git a/cmds/statsd/Android.mk b/cmds/statsd/Android.mk
index 67b9089..740fdc0 100644
--- a/cmds/statsd/Android.mk
+++ b/cmds/statsd/Android.mk
@@ -116,10 +116,8 @@
 
 LOCAL_CFLAGS += \
     -Wall \
+    -Wextra \
     -Werror \
-    -Wno-missing-field-initializers \
-    -Wno-unused-variable \
-    -Wno-unused-function \
     -Wno-unused-parameter
 
 ifeq (debug,)