cat: Unrevert splice patch (#2020)

* cat: Unrevert splice patch

* cat: Add fifo test

* cat: Add tests for error cases

* cat: Add tests for character devices

* wc: Make sure we handle short splice writes

* cat: Fix tests for 1.40.0 compiler

* cat: Run rustfmt on test_cat.rs

* Run 'cargo +1.40.0 update'

tests/by-util/test_wc.rs

@@ -1,5 +1,33 @@
 use crate::common::util::*;
 
+#[test]
+fn test_count_bytes_large_stdin() {
+    for &n in &[
+        0,
+        1,
+        42,
+        16 * 1024 - 7,
+        16 * 1024 - 1,
+        16 * 1024,
+        16 * 1024 + 1,
+        16 * 1024 + 3,
+        32 * 1024,
+        64 * 1024,
+        80 * 1024,
+        96 * 1024,
+        112 * 1024,
+        128 * 1024,
+    ] {
+        let data = vec_of_size(n);
+        let expected = format!("{}\n", n);
+        new_ucmd!()
+            .args(&["-c"])
+            .pipe_in(data)
+            .succeeds()
+            .stdout_is_bytes(&expected.as_bytes());
+    }
+}
+
 #[test]
 fn test_stdin_default() {
     new_ucmd!()