Be compliant with new cmake policy CMP0072 with cmake > 3.11

Description

OTB is not compliant with the behaviour of the cmake policy 3.11 related to OpenGL find_package:

https://cmake.org/cmake/help/v3.11/policy/CMP0072.html

Steps to reproduce

Describe as precisely as possible how to reproduce the bug. Try to isolate a minimal number of steps. Also describe reproducibility (always, random ...).

Configuration information

OS, OTB version or tag, information related to build (binaries, superbuild, system libs ...)