GMPLS update - 38: adding in-segment interface index

Added #mpls-interface based #indexing on #in-segment configuration entries in GMPLS module. This will help in doing #search #operations among the in-segment entries for #specific #interfaces in a #quick and #efficient manner. On #interface #changes the events are #forwarded to all the segments created on the interface. From segments the events #chained to #cross-connects and then further to the parent #tunnel #LSPs. On maintaining the interface index on segments expedite the event chaining process. The mpls-interface is used as an index in to the segment.

#GMPLS update 38 ...
[commit 32ce164730ccf7d8a27971e6354018e0144ee081] (https://github.com/nes-repo/NES-Open-Switch/commit/32ce164730ccf7d8a27971e6354018e0144ee081)