Rollup merge of #154003 - ginnyTheCat:uefi-file-send, r=Mark-Simulacrum

Make std::fs::File Send on UEFI

Similarly to rust-lang/rust#150990 since UEFI has no threads, this should be safe.

library/std/src/sys/fs/uefi.rs

@@ -588,6 +588,11 @@ pub(crate) struct File {
         path: crate::path::PathBuf,
     }
 
+    // SAFETY: UEFI has no regular threads, and as per <https://github.com/rust-lang/rust/issues/133604>
+    // std does not support being invoked from "irregular threads" such as interrupt handlers or other
+    // CPU cores that run outside the scope of UEFI.
+    unsafe impl Send for File {}
+
     impl File {
         pub(crate) fn from_path(path: &Path, open_mode: u64, attr: u64) -> io::Result<Self> {
             let absolute = crate::path::absolute(path)?;