std: xous: mark stdio structs as repr(C)

Ensure these structs have a well-defined ABI layout.

Signed-off-by: Sean Cross <[email protected]>

Author: xobs

library/std/src/sys/xous/stdio.rs

@@ -27,7 +27,7 @@ impl Stdout {
 
 impl io::Write for Stdout {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        #[repr(align(4096))]
+        #[repr(C, align(4096))]
         struct LendBuffer([u8; 4096]);
         let mut lend_buffer = LendBuffer([0u8; 4096]);
         let connection = log_server();
@@ -53,7 +53,7 @@ impl Stderr {
 
 impl io::Write for Stderr {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        #[repr(align(4096))]
+        #[repr(C, align(4096))]
         struct LendBuffer([u8; 4096]);
         let mut lend_buffer = LendBuffer([0u8; 4096]);
         let connection = log_server();