Add fastpath for srb2p relevant variables in lib_getenum.

After the globalize work done on the LUA side of things, lib_getenum usage while idling in monad was profiled to still be around ~0.26%(originally at 5%). This commit, while a hack, manages to reduce overhead to about ~0.06%. The Lua stuff should ideally be actually preventing the variables from being processed outright, but for some reason, it's still happening, though at a far lesser rate when I did the first comparison of performance. The only thing blocking this MR would be the stupidity of this code, if a better solution is desired I can close this when that is the case.