Unit test failures under Emscripten

[Maratyszcza]

fp16_alt_to_fp32_value and fp16_ieee_to_fp32_value fail the unit test under Emcripten/Asm.js:

[  FAILED  ] 1 test, listed below:
[  FAILED  ] FP16_ALT_TO_FP32_VALUE.negative_denormalized_values

[  FAILED  ] FP16_IEEE_TO_FP32_VALUE.negative_normalized_values
[  FAILED  ] FP16_IEEE_TO_FP32_VALUE.negative_denormalized_values

As a workaround, fp16_alt_to_fp32_bits and fp16_ieee_to_fp32_bits can be used instead.