Revert "Merge pull request #7 from gwtnb/libc++"

This reverts commit 91a4656e601e2a9759e19e90cbfaa037c290ba44, reversing
changes made to eea93558b154dffdb279606fa421f2c27a384c4e.

Commit 91a4656e601e2a9759e19e90cbfaa037c290ba44 breaks Jubatus build.