Similar to both #417 and #418. Fixes errors when PCL_NO_PRECOMPILE=ON

[chambbj]

referenced in #521

[taketwo]

Shouldn't explicit template instantiation in 'octree_inst.cpp' be ifndef'ed then?

[taketwo]

@chambbj Sorry for the delay. Actually github does not send notifications when a new commit is added to a pull request, so we have no means to learn about your activity unless you also comment after pushing new stuff.

Regarding the PR itself. The "test" run on Travis failed. (Not because of your modification, but for some other reasons. It happens some times). But it would be nice to see it succeeding. Could you please squash the two commits and push again? This way we'll kill two birds with one stone: commit history will be prettier and Travis will re-run tests. Thanks!

[chambbj]

@taketwo No problem. Pushed!

[chambbj]

Ugh, it would help if I remembered to build with PCL_NO_PRECOMPILE=ON. I'll get back to you @takewo.

[chambbj]

@taketwo We should be good now.

[taketwo]

So you fixed those undefined references to OctreeBase::xxx in the previous build by tweaking 'voxel_grid_occlusion_estimation', 'line_rgbd', and 'poisson'? Seems totally unrelated at the first glance, how did you figure this out?

[chambbj]

@taketwo No, the undefined references originally occurred because I had the #ifdef PCL_NO_PRECOMPILE located before the class exports. The tweaks to voxel_grid_occlusion estimation, line_rgbd, and poisson were in response to compiler errors that appeared after the first change.

[taketwo]

Ah, I see.