PCL requires C++14 or above

[moooeeeep]

The cmake setting would cause compilation with C++11 set, which apparantly doesn't work anymore (with Ubuntu 20.04 at least)

[moooeeeep]

Related recent edits:

• https://github.com/envire/envire-envire_pcl/commit/725cc8da2efb8bc4ee2ae5f4d557283fe50d6fcd
• https://github.com/envire/envire-envire_collision/commit/2204b43f81552aca45f82891b882e6369421414d

@planthaber

[moooeeeep]

Probably this should be adjusted for other envire_* packages, e.g.:

• https://github.com/envire/envire-envire_octomap/blob/master/CMakeLists.txt#L4
• https://github.com/envire/envire-envire_visualizer/blob/master/CMakeLists.txt#L2