mnesia: Optimize locker
mnesia: Optimize locker

Many read locks on the same record was kept in a list, which caused
very long lookup and insert times.

Optimize by using a tuple of size 1, and use select instead of lookup,
this works since it is ordered_set.

jj1bdx/otp,mikpe/otp,potatosalad/otp,potatosalad/otp,jj1bdx/otp,rlipscombe/otp,rlipscombe/otp,bjorng/otp,g-andrade/otp,mikpe/otp,jj1bdx/otp,mikpe/otp,mikpe/otp,bjorng/otp,vinoski/otp,erlang/otp,bjorng/otp,dumbbell/otp,emacsmirror/erlang,bjorng/otp,mikpe/otp,vinoski/otp,emacsmirror/erlang,mikpe/otp,bjorng/otp,erlang/otp,dgud/otp,g-andrade/otp,dumbbell/otp,g-andrade/otp,vinoski/otp,mikpe/otp,isvilen/otp,potatosalad/otp,jj1bdx/otp,dumbbell/otp,rlipscombe/otp,bjorng/otp,rlipscombe/otp,erlang/otp,dumbbell/otp,potatosalad/otp,dgud/otp,vinoski/otp,vinoski/otp,dumbbell/otp,bjorng/otp,isvilen/otp,dumbbell/otp,isvilen/otp,erlang/otp,g-andrade/otp,rlipscombe/otp,dgud/otp,mikpe/otp,mikpe/otp,dgud/otp,isvilen/otp,dgud/otp,vinoski/otp,jj1bdx/otp,dgud/otp,emacsmirror/erlang,rlipscombe/otp,dumbbell/otp,bjorng/otp,g-andrade/otp,emacsmirror/erlang,jj1bdx/otp,g-andrade/otp,potatosalad/otp,isvilen/otp,dumbbell/otp,erlang/otp,isvilen/otp,bjorng/otp,isvilen/otp,g-andrade/otp,isvilen/otp,emacsmirror/erlang,emacsmirror/erlang,erlang/otp,dgud/otp,jj1bdx/otp,dgud/otp,isvilen/otp,erlang/otp,erlang/otp,vinoski/otp,rlipscombe/otp,emacsmirror/erlang,potatosalad/otp,potatosalad/otp,g-andrade/otp,rlipscombe/otp,rlipscombe/otp,potatosalad/otp,jj1bdx/otp,jj1bdx/otp,erlang/otp,mikpe/otp,vinoski/otp,vinoski/otp,potatosalad/otp,emacsmirror/erlang,vinoski/otp,dgud/otp,potatosalad/otp,g-andrade/otp,dumbbell/otp,emacsmirror/erlang,erlang/otp,g-andrade/otp,dgud/otp,bjorng/otp,jj1bdx/otp,isvilen/otp,rlipscombe/otp,dumbbell/otp,emacsmirror/erlang