Based on an idea from Brian move the libevent trigger update to a later
stage instead of the generic add/del procs. So, we are doing the
increment/decrement when we register the recv handler for an endpoint,
so basically when we create and connect a socket to a peer. The benefit
is that as long as TCP is not used, there should be no impact on the
performance of other BTLs. The drawback is that the first TCP connection
will be slightly slower, but then once we have a peer connected over
TCP things go back to normal.
Signed-off-by: George Bosilca <bosilca@icl.utk.edu>