Add compression speed test bench

test/bench/3rdparty_licenses/LICENSE.BSD-3.Zstandard

test/bench/3rdparty_licenses/LICENSE.GPL-2

test/bench/bench.c

test/bench/benchfn.c

test/bench/benchfn.h

test/bench/io.h

test/bench/leon3_grtimer.c

test/bench/leon3_grtimer.h

test/bench/leon3_grtimer_longcount.c

test/bench/leon3_grtimer_longcount.h

test/bench/leon3_timers.h

test/bench/leon_reg.h

test/bench/meson.build

test/bench/ref_short_cadence_1_cmp.h

test/bench/ref_short_cadence_2_cmp.h

test/bench/timefn.c

test/bench/timefn.h

test/meson.build