remove obsolete function diverge

Author: stlankes

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

@@ -334,10 +334,6 @@ impl File {
     pub fn set_permissions(&self, _perm: FilePermissions) -> io::Result<()> {
         Err(Error::from_raw_os_error(22))
     }
-
-    pub fn diverge(&self) -> ! {
-        loop {}
-    }
 }
 
 impl DirBuilder {