1. Add FIELD_COUNT_REPEATED bit masks to repeated fields that were previously missing

2. Resolve segfault when serializing proto into vector of uint8_t
3. Add a local byte size variable for EventMetric data as we cannot call
size() of ProtoOutputStream before we finish writing.
4. Replace hardcoded conversion of second to nano second with NS_PER_SEC

Test: statsd, statsd_test

Change-Id: I47a2ce2b05e6191c18596489682118edcb41e945