[OPTIM] ebmbtree: optimise insertion to avoid duplication of bit computation
[OPTIM] ebmbtree: optimise insertion to avoid duplication of bit computation

The call to equal_bits() is repeated at several places and this code is large.
By centralising this call, we can substantially reduce the size of the code
and at the same time speed the function up by about 15%. The same optimisation
will have to be performed on ebsttree.

sociomantic-tsunami/ebtree,haproxy/ebtree,sociomantic-tsunami/ebtree