[libc][NFC] Adjust sinf and cosf around -infinity inputs.

The current tests verify if the result of -infinity is a quiet NaN with
sign bit set. But, that need not be the case on all platforms. So, just
checking that the result is a quiet NaN and ignoring the sign bit is
good enough.

GitOrigin-RevId: ef0ea8717a9b513d2bf67c2b04b876700593fa07
2 files changed