Add bytes interface to LogEvent for pulled atoms

This adds a writeBytes interface to LogEvent for native pulled atoms,
which have been using write(string). The function still takes in a
string, but instead uses the write_char_array interface to avoid
stopping on null termination.

Test: modified tests and ran statsd_test
Test: statsd_testdrive 10055 to test against gpu app stats
Bug: 141965020
Change-Id: Iaedfb73310769165d8b61affb55e784f109355cf