llist: Add a C++ wrapper for linux_list

This commit adds the LListHead class which is a wrapper around the
linuxlist. It adds an additional member to refer to the container,
since the container_of macro doesn't work properly with C++ classes.
All functions and macros from linuxlist.h are support except for the
entry macros (e.g. llist_entry, llist_for_each_entry, ...). To access
the container (entry), an entry() method is provided instead:

  llist_for_each(pos, &elems) {
      pos->entry()->do_something();
  }

Sponsored-by: On-Waves ehf
diff --git a/tests/llist/LListTest.ok b/tests/llist/LListTest.ok
new file mode 100644
index 0000000..375e9a6
--- /dev/null
+++ b/tests/llist/LListTest.ok
@@ -0,0 +1,10 @@
+=== start test_linux_list ===
+ 1 -> number one
+ 2 -> number two
+ 3 -> number three
+ 1 -> number one
+ 2 -> number two
+ 3 -> number three
+ 1 -> number one
+ 2 -> number three
+=== end test_linux_list ===