Supply the 3rd template parameter to unordered_map.
Supply the 3rd template parameter to unordered_map.

Really it is just the default parameter, but apple's gcc is buggy
and therefore requires it.


git-svn-id: 0a20d38d1bcdb3210d244a647211d61b0aabf366@229 5b8196f7-c1c0-4be6-8b13-4feed349168d

BlueBrain/Tuvok,BlueBrain/Tuvok,BlueBrain/Tuvok