GMPLS update - 80: optimizing tunnel session attribute

Updated #session-attribute parameter for #MPLS-Tunnel in GMPLS module. The parameter size has been fixed to specific bytes and hence the #length variable for the parameter has been removed. The agent handler for this parameter has been updated to remove the variable length from use. This reduces the memory required to hold the session-attribute parameter. The session-attribute will keep track of the parameters like #fast-reroute-enabled, #merging-permitted, #persistence-enabled, #route-pinned, #record-route, etc... The fast-reroute-enabled parameter enables the upstream node to safely reroute the tunnel on a downstream link or node failure using a local-repair mechanism. The merging-permitted parameter enables the transit routers to merge the tunnels with the same destination, this is used on a resource crunch or better scaling of the network. The persistence-enabled parameter causes to automatically retry to reestablish the tunnel on a failure. The route-pinned parameter causes the dynamically computed path to be used permanently as an explicit-path. The record-route parameter causes the transit routes to be recorded and send back to the tunnel head-node.

#GMPLS update 80 ...
[commit a4073c75ca03c7747e816a49fcf17ed5643f9b1c] (https://github.com/nes-repo/NES-Open-Switch/commit/a4073c75ca03c7747e816a49fcf17ed5643f9b1c)