Replace glVertexPointer_p() call with glVertexPointer_c(). (#3677)
Replace glVertexPointer_p() call with glVertexPointer_c(). (#3677)

Delete VBO buffers after they've been drawn. Both ways work on OpenGL.pm 0.7

Credit to @bubnikv from prusa3d fork, drawn from commit c0b3de6248f6e6d50624b3d2132c823fb65af95e on that repository.
lordofhyphens/Slic3r,platsch/Slic3r,lordofhyphens/Slic3r,alexrj/Slic3r,pieis2pi/Slic3r,curieos/Slic3r,alexrj/Slic3r,mcilhargey/Slic3r,pieis2pi/Slic3r,tmotl/Slic3r,tmotl/Slic3r,tmotl/Slic3r,curieos/Slic3r,tmotl/Slic3r,curieos/Slic3r,alexrj/Slic3r,mcilhargey/Slic3r,xoan/Slic3r,alexrj/Slic3r,xoan/Slic3r,platsch/Slic3r,mcilhargey/Slic3r,pieis2pi/Slic3r,mcilhargey/Slic3r,tmotl/Slic3r,pieis2pi/Slic3r,lordofhyphens/Slic3r,lordofhyphens/Slic3r,tmotl/Slic3r,alexrj/Slic3r,platsch/Slic3r,curieos/Slic3r,curieos/Slic3r,mcilhargey/Slic3r,mcilhargey/Slic3r,pieis2pi/Slic3r,mcilhargey/Slic3r,xoan/Slic3r,curieos/Slic3r,lordofhyphens/Slic3r,xoan/Slic3r,pieis2pi/Slic3r,xoan/Slic3r,alexrj/Slic3r,platsch/Slic3r,platsch/Slic3r,lordofhyphens/Slic3r,xoan/Slic3r,platsch/Slic3r