These microbenchmarks will allow us to measure the performance impact of
FP emulation optimizations. Note that we can measure both directly the impact
on the softfloat functions (with "-t soft"), or the impact on an
emulated workload (call with "-t host" and run under qemu user-mode).
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NEmilio G. Cota <cota@braap.org>
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>

By leveraging berkeley's softfloat and testfloat.

With this we get decent coverage of softfloat.c:

$ ./fp-test -r even:	67.22% coverage
$ ./fp-test -r all:	73.11% coverage

Note that we do not yet test parts of softfloat.c that aren't
in the original softfloat library, namely:

- denormal inputs
- *_to_int16/uint16 conversions
- scalbn for fixed point
- muladd variants
- min/max
- exp2
- log2
- float*_compare (except float16_compare)
Signed-off-by: NEmilio G. Cota <cota@braap.org>
[rth: Add the new modules to git_submodules.]
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>