Since G_TEST_GET_FULL_NAME is not initialized in the benchmark framework,
benchmarks using the unit test setup run in the same directory without
any clear distinction between them.
This poses an extra complication for locating any specific benchmark
directory during a failure.
In master, unit tests and benchmarks run in the following path:
/<OS_tmp_dir>/test_common bitcoin/<random_uint256>/
After this commit, unit tests and benchmarks are contained within its
own directory:
/<OS_tmp_dir>/test_common bitcoin/<test_name>/<time_in_nanoseconds>/
This makes it easier to find any benchmark run when a failure occurs.
ad9c2cceda