remove deprecated primitive type

[thorseraq]

Since primitive types defined at https://github.com/rust-lang/rust/tree/4331c151b09a065f6b3bedf4158edc336317bc0d/library/core/src/num/shells are going to be deprecated and will be replaced by types defined at https://github.com/rust-lang/rust/blob/4331c151b09a065f6b3bedf4158edc336317bc0d/library/core/src/num/mod.rs which has been stable since 1.0.0, It seems a good time to update the corresponding implementations to align with these changes

[Darksonn]

It seems like this is not possible on bytes's minimum supported rust version:

  error[E0599]: no associated item named `MAX` found for type `usize` in the current scope
     --> src/bytes_mut.rs:104:35
      |
  104 | const MAX_VEC_POS: usize = usize::MAX >> VEC_POS_OFFSET;
      |                                   ^^^ associated item not found in `usize`
  
  error[E0599]: no associated item named `MAX` found for type `isize` in the current scope
      --> src/buf/buf_mut.rs:1576:16
       |
  1576 |         isize::MAX as usize - self.len()
       |                ^^^ associated item not found in `isize`
  
  error[E0599]: no associated item named `MAX` found for type `usize` in the current scope
      --> src/bytes.rs:1108:26
       |
  1108 |     if old_size > usize::MAX >> 1 {
       |                          ^^^ associated item not found in `usize`
  
  error[E0599]: no associated item named `MAX` found for type `usize` in the current scope
      --> src/bytes_mut.rs:1085:16
       |
  1085 |         usize::MAX - self.len()
       |                ^^^ associated item not found in `usize`
  
  error[E0599]: no associated item named `MAX` found for type `isize` in the current scope
      --> src/bytes_mut.rs:1338:26
       |
  1338 |     if old_size > isize::MAX as usize {
       |                          ^^^ associated item not found in `isize`
  
  error: aborting due to 5 previous errors

[thorseraq]

It seems like this is not possible on bytes's minimum supported rust version:

Sorry, yes: https://github.com/rust-lang/rust/blob/1.39.0/src/libcore/num/mod.rs, I'll close this :)