logd: add tests for log deduplication

Fix a subtle bug that liblog event messages have a payload of int32_t,
not uint32_t, so they should only be summed to int32_t max.

Make a bunch of test improvements as well to support these.

Test: these tests
Change-Id: I4069cc546240bfffec5b19f34ebec913799674e8
diff --git a/logd/Android.bp b/logd/Android.bp
index 7e58f07..5e591d9 100644
--- a/logd/Android.bp
+++ b/logd/Android.bp
@@ -125,10 +125,7 @@
         "-Wextra",
         "-Werror",
         "-fno-builtin",
-
-        "-DAUDITD_LOG_TAG=1003",
-        "-DCHATTY_LOG_TAG=1004",
-    ],
+    ] + event_flag,
 
     srcs: [
         "logd_test.cpp",