lib/classifier: Clarify trie_lookup_value().

trie_lookup_value() is easier to read with the local variable 'plen'
renamed as 'ofs'.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
lib/classifier: Fix use of uninitialized memory.

When reaching the end of a prefix trie, we checked one bit off the end
to the intended data.  However, since the trie node in that case has
NULLs for both edge links, this did not result in incorrect
functionality.

Found via check-valgrind.

Reported-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>