Revert "Fixed a bug in FLANN resulting in uninitialized accesses."

This reverts commit a9975b144a22e76228125eb0a25f78ec13db6815, to prepare
for cherry-picking upstream's solution.
Cherry-picked mariusmuja/flann@b615f2694723fe402b8bbe50d77e622beff7f171.

Original author: Alex Wilson.
Cherry-picked mariusmuja/flann@8c8b0e0cb879666797ab2ac51b9ee438bf84a183.

Original author: me.
Merge pull request #1550 from SpecLad:flann-uninit-master