Instead use float one by default for sample rate conversions.
The s16p internal transfer format produces visible and hearable
quantization artifacts.
Signed-off-by: Paul B Mahol <onemda@gmail.com>

for S8 we continue to use S16 as it should have enough precision
Fate is adjusted so bitexactness is maintained between mips/arm/x86
if more tests became bit-inexact on some platform, the same change
can be done to them

The use of higher precision and float intermediates inevitably
leads to more differences between platforms.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>