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/PrivacyBuffer.cpp b/cmds/incidentd/src/PrivacyBuffer.cpp
index 73ee1cb..f1f7c589 100644
--- a/cmds/incidentd/src/PrivacyBuffer.cpp
+++ b/cmds/incidentd/src/PrivacyBuffer.cpp
@@ -101,7 +101,7 @@
 }
 
 // ================================================================================
-PrivacyBuffer::PrivacyBuffer(const Privacy* policy, EncodedBuffer::iterator& data)
+PrivacyBuffer::PrivacyBuffer(const Privacy* policy, EncodedBuffer::iterator data)
     : mPolicy(policy), mData(data), mProto(), mSize(0) {}
 
 PrivacyBuffer::~PrivacyBuffer() {}