hush: fix comment parsing in `cmd`, closes 10421

function                                             old     new   delta
parse_stream                                        2692    2690      -2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash_test/ash-parsing/comment2.right b/shell/ash_test/ash-parsing/comment2.right
new file mode 100644
index 0000000..ee6e49a
--- /dev/null
+++ b/shell/ash_test/ash-parsing/comment2.right
@@ -0,0 +1,4 @@
+Ok1
+Ok2
+Ok5
+Ok6