Optimize incidentd memory usage

1. Remove dependency of libprotobuf-cpp-lite, saves .so mmap ~200KB
2. Don't use auto except iterator for readability.

Bug: 74254200
Test: adb shell dumpsys meminfo `pid incidentd`
Change-Id: If6198521c3b80929d6ea3f7ed466b5195991ccfd
diff --git a/cmds/incidentd/src/Reporter.h b/cmds/incidentd/src/Reporter.h
index ba8965e..f9a092a 100644
--- a/cmds/incidentd/src/Reporter.h
+++ b/cmds/incidentd/src/Reporter.h
@@ -66,6 +66,7 @@
     int mainFd() { return mMainFd; }
     int mainDest() { return mMainDest; }
     IncidentMetadata& metadata() { return mMetadata; }
+    map<int, IncidentMetadata::SectionStats>& allSectionStats() { return mSectionStats; }
 
     bool containsSection(int id);
     IncidentMetadata::SectionStats* sectionStats(int id);
@@ -77,7 +78,7 @@
     int mMainDest;
 
     IncidentMetadata mMetadata;
-    map<int, IncidentMetadata::SectionStats*> mSectionStats;
+    map<int, IncidentMetadata::SectionStats> mSectionStats;
 };
 
 // ================================================================================