Add logf and log2f benchmark

Similar to expf/exp2f, this patch add two benchmarks for logf and log2f:
one which measures thoughput and one which measures latency.

The input data is based on a reduced trace based on 2.8 billion samples
extracted from specpu2017 521.wrf_r benchmark.

Test: ran 32-bit and 64-bit x86 tests on host
Change-Id: If4fbd7eb3d40f8e155935149a82f162b222d5506