linux: add devmem structs

For reference:
   https://elixir.bootlin.com/linux/v6.13.5/source/include/uapi/linux/uio.h#L23

Signed-off-by: Pedro Tammela <pctammela@gmail.com>

(backport <#4299>)
(cherry picked from commit 4985e60)

Author: tammela

libc-test/build.rs

@@ -4135,6 +4135,10 @@ fn test_linux(target: &str) {
             // FIXME(linux): Requires >= 6.9 kernel headers.
             "epoll_params" => true,
 
+            // FIXME(linux): Requires >= 6.12 kernel headers.
+            "dmabuf_cmsg" |
+            "dmabuf_token" => true,
+
             _ => false,
         }
     });

src/unix/linux_like/linux/mod.rs

@@ -1320,6 +1320,21 @@ s! {
         pub propagation: crate::__u64,
         pub userns_fd: crate::__u64,
     }
+
+    // linux/uio.h
+
+    pub struct dmabuf_cmsg {
+        pub frag_offset: crate::__u64,
+        pub frag_size: crate::__u32,
+        pub frag_token: crate::__u32,
+        pub dmabuf_id: crate::__u32,
+        pub flags: crate::__u32,
+    }
+
+    pub struct dmabuf_token {
+        pub token_start: crate::__u32,
+        pub token_count: crate::__u32,
+    }
 }
 
 cfg_if! {