Implement _BitInt #36
Description
We should implement C23 _BitInt. We would only need to support up to _BitInt(64).
From the C23 standard:
The value BITINT_MAXWIDTH shall expand to a value that is greater than or equal to the value of ULLONG_WIDTH
Three possible ways of implementing things:
sizeof(_BitInt(40))is 5sizeof(_BitInt(40))is 6 (__int48)sizeof(_BitInt(40))is 8 (long long)