[RFC] Helpers for integer(_su) arithmetic to prevent overflow and/or underflow

[lum1n0us]

• for performance sensitive logic, use __builtin_add_overflow etc. provide something like https://github.com/yamt/toywasm/blob/9a5622791e99395e26e6e96cef830af3d91a1685/lib/platform.h#L176-L191 and encourage the use of them.

Originally posted by @yamt in #4549 (comment)