Strict integer subtraction. Computes `self - rhs`, panicking if overflow occurred.
# Panics
## Overflow behavior
This function will always panic on overflow, regardless of whether overflow checks are enabled.
# Examples
Basic usage:
```
# use ::exint::primitive::*;
# ::exint::uint! {
assert_eq!((i24::MIN + 2_i24).strict_sub(1_i24), i24::MIN + 1_i24);
# }
```
The following panics because of overflow:
```should_panic
# use ::exint::primitive::*;
# ::exint::uint! {
let _ = (i24::MIN + 2_i24).strict_sub(3_i24);
# }
```