[GPU] Tests need several hacks to compile

I did some hacks to run it on my side

Such as?

It's expected that GTest is bundled, which is no longer true:

• https://github.com/PointCloudLibrary/pcl/blob/pcl-1.10.0/gpu/features/test/CMakeLists.txt#L5-L10

Sources are collected but not used anywhere:

• https://github.com/PointCloudLibrary/pcl/blob/pcl-1.10.0/gpu/features/test/CMakeLists.txt#L24-L27

I see that PCL using PCL_ADD_TEST wrapper for add_test. It can't be used
there because it needs custom tests target:

• https://github.com/PointCloudLibrary/pcl/blob/pcl-1.10.0/cmake/pcl_targets.cmake#L391

Which is created here:

• https://github.com/PointCloudLibrary/pcl/blob/pcl-1.10.0/test/CMakeLists.txt#L19

Since subdirectory gpu will be processed before subdirectory test this target will not be available:

• https://github.com/PointCloudLibrary/pcl/blob/pcl-1.10.0/CMakeLists.txt#L481-L483

Path to tested *.pcd file is hardcoded:

• https://github.com/PointCloudLibrary/pcl/blob/pcl-1.10.0/gpu/features/test/data_source.hpp#L82

Tested file office_chair_model.pcd is missing:

• https://github.com/PointCloudLibrary/pcl/tree/pcl-1.10.0/test

I found it, put it in the root folder and have to run the test from there, without using CTest.

I did some trivial tweaks to fix few places but most of the tests failing even without patch. List of tests I have to exclude:

PCL_FeaturesGPU.PrincipalCurvatures
PCL_FeaturesGPU.pfh_high_level1
PCL_FeaturesGPU.pfh_high_level2
PCL_FeaturesGPU.pfh_high_level3
PCL_FeaturesGPU.pfh_high_level4
PCL_FeaturesGPU.pfh_low_level
PCL_FeaturesGPU.pfhrgb
PCL_FeaturesGPU.ppf
PCL_FeaturesGPU.ppfrgb
PCL_FeaturesGPU.vfh1
PCL_FeaturesGPU.vfh_fill_size_component_true
PCL_FeaturesGPU.vfh_norm_bins_false
PCL_FeaturesGPU.vfh_norm_distance_true

Originally posted by @ruslo in https://github.com/PointCloudLibrary/pcl/pull/3627#issuecomment-582896648

Inspect gpu/features/test/CMakeLists.txt, gpu/features/test/data_source.hpp, cmake/pcl_targets.cmake, and the top-level CMakeLists.txt. Run the GPU feature tests through CTest and use the listed missing file, target-order, and failing-test details as checks; done means the tests configure and run without manual hacks or exclusions.