utils/viewer: set default OpenGL version to 4.1
utils/viewer: set default OpenGL version to 4.1

Target by default the same OpenGL version that the one given by recent
OSX releases. Good drivers will anyway give us an higher OpenGL version
which is a superset of the one we request on other platforms.

gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl