Switch almost all of Pal to Rusty error handling.

src/header/sys_random/mod.rs

@@ -1,6 +1,9 @@
 use core::slice;
 
-use crate::platform::{types::*, Pal, Sys};
+use crate::{
+    error::ResultExt,
+    platform::{types::*, Pal, Sys},
+};
 
 pub const GRND_NONBLOCK: c_uint = 1;
 pub const GRND_RANDOM: c_uint = 2;
@@ -11,4 +14,5 @@ pub unsafe extern "C" fn getrandom(buf: *mut c_void, buflen: size_t, flags: c_ui
         slice::from_raw_parts_mut(buf as *mut u8, buflen as usize),
         flags,
     )
+    .or_minus_one_errno()
 }