Separate these tests such that future log buffer implementations can
be run against the generic tests. Use a parameterized fixture to
allow testing any number of log buffers.
Test: these unit tests
Change-Id: I6d90838e8efa019b934d08da25cab0c2405b66cd
Fix a subtle bug that liblog event messages have a payload of int32_t,
not uint32_t, so they should only be summed to int32_t max.
Make a bunch of test improvements as well to support these.
Test: these tests
Change-Id: I4069cc546240bfffec5b19f34ebec913799674e8
Add a standalone test of log buffers that does not interact with the
logd running on the device.
Test: this new test
Change-Id: Ie4ecc50289ef164aa47cc72ddeeb9b28e776db94
