classifier: Use ccmaps for staged lookup indices.

classifier: Use ccmaps for staged lookup indices.

Use the new ccmap type instead of cmap for staged lookup indices to
fix the problem with slow removal of rules with large number of
duplicates.  This was problematic especially when many rules shared
the same match in packet metadata (e.g., a port number, but nothing
else), causing a large number of duplicates to be inserted into the
staged lookup index.  ccmap only keeps the count of inserted (hash)
values, so duplicates do not add any performance penalty.

Reported-by: Alok Kumar Maurya <alok-kumar.maurya@hpe.com>
Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>