Since s_sinf.c either assigns the return value of floor to integer or
passes double converted from integer to floor, this patch replaces
floor with simple casts.
Also since long == int for 32-bit targets, we can use long instead of
int to avoid 64-bit integer for 64-bit targets.
On Skylake, bench-sinf reports performance improvement:
Before After Improvement
max 130.566 129.564 30%
min 7.704 7.706 0%
mean 21.8188 19.1363 30%
* sysdeps/ieee754/flt-32/s_sinf.c (reduced): Replace long with
int.
(SINF_FUNC): Likewise. Replace floor with simple casts.