Merge pull request #12660 from alalek:flann_drop_useless_mutex
authorAlexander Alekhin <alexander.a.alekhin@gmail.com>
Thu, 27 Sep 2018 19:46:59 +0000 (19:46 +0000)
committerAlexander Alekhin <alexander.a.alekhin@gmail.com>
Thu, 27 Sep 2018 19:46:59 +0000 (19:46 +0000)

Trivial merge