mem: add sane default parameter

This is also the default for the types in the `alloc` crate

Author: phip1611

uefi/src/mem/util.rs

@@ -9,6 +9,8 @@ use core::slice;
 
 #[cfg(not(feature = "unstable"))]
 use ::alloc::alloc::{alloc, dealloc};
+#[cfg(feature = "unstable")]
+use alloc::alloc::Global;
 
 #[cfg(feature = "unstable")]
 use {core::alloc::Allocator, core::ptr::NonNull};
@@ -39,7 +41,7 @@ pub(crate) fn make_boxed<
     // The UEFI data structure.
     Data: Align + ?Sized + Debug + 'a,
     F: FnMut(&'a mut [u8]) -> Result<&'a mut Data, Option<usize>>,
-    #[cfg(feature = "unstable")] A: Allocator,
+    #[cfg(feature = "unstable")] A: Allocator = Global,
 >(
     // A function to read the UEFI data structure into a provided buffer.
     mut fetch_data_fn: F,