package/kodi-visualisation-shadertoy: needs libglew for OpenGL build

package/kodi-visualisation-shadertoy: needs libglew for OpenGL build

Fixes
-- Found OpenGL: /home/bernd/buildroot/output/host/usr/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/lib/libGL.so
CMake Error at /home/bernd/buildroot/output/host/usr/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:148
 (message):
  Could NOT find GLEW (missing: GLEW_INCLUDE_DIRS GLEW_LIBRARIES)

For details have a look at
https://github.com/notspiff/visualization.shadertoy/blob/master/CMakeLists.txt#L21

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>