Avoid usage of the unstable Allocator trait

And also optimize init_sections to use the fact that allocate_frames
returns zeroed frames.

src/common/mod.rs

@@ -1,10 +1,3 @@
-use core::alloc::Allocator;
-
-use alloc::boxed::Box;
-use alloc::vec::Vec;
-
-use crate::memory::Enomem;
-
 pub mod aligned_box;
 #[macro_use]
 pub mod int_like;
@@ -34,13 +27,4 @@ macro_rules! dbg {
     };
 }
 
-pub fn try_new_vec_with_exact_size<T, A: Allocator>(len: usize, alloc: A) -> Result<Vec<T, A>, Enomem> {
-    let mut vec = Vec::<T, A>::new_in(alloc);
-    vec.try_reserve_exact(len).map_err(|_| Enomem)?;
-    Ok(vec.into())
-}
-pub fn try_box_slice_new<T, A: Allocator>(value: impl FnMut() -> T, len: usize, alloc: A) -> Result<Box<[T], A>, Enomem> {
-    let mut vec = try_new_vec_with_exact_size(len, alloc)?;
-    vec.resize_with(len, value);
-    Ok(vec.into())
-}
+