split: catch broken pipe error for round robin strategy

The broken pipe error is not handled in the case of the round robin
strategy (typically used with --filter).

Align to the other strategies to silence that error in that use case
too.

fixes #5191

Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>

tests/by-util/test_split.rs

@@ -299,6 +299,18 @@ fn test_filter_command_fails() {
         .fails();
 }
 
+#[test]
+#[cfg(unix)]
+fn test_filter_broken_pipe() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let name = "filter-big-input";
+
+    RandomFile::new(&at, name).add_lines(1024 * 10);
+    ucmd
+        .args(&["--filter=head -c1 > /dev/null", "-n", "r/1", name])
+        .succeeds();
+}
+
 #[test]
 fn test_split_lines_number() {
     // Test if stdout/stderr for '--lines' option is correct