logd: multiple identical do not report expired

Report multiple identical chatty messages differently than for
regular expire chatty messages.  Multiple identical will
report identical count, while spam filter will report
expire count.

This should reduce the expected flood of people confused
but chatty messages in continuous logcat output.

Test: gTest logd_unit_tests --gtest_filter=logd.multiple*
Change-Id: Iad93d3efc6a3938a4b87ccadddbd86626a015d44