Support big integers in the compiler

[tekknolagi]

Candidates:

• Austin Henley's: https://github.com/AZHenley/bignum/blob/main/bignum.c
• https://github.com/983/bigint or https://github.com/983/Num
• Just do it by hand from Hacker's Delight
• https://github.com/adam-mcdaniel/bigint