On macOS, use NSOpenGLProfileVersion4_1Core when requesting an OpenGL 4.1 context

Currently, when requesting an OpenGL 4.1 context on macOS, the Qt implementation will use the NSOpenGLProfileVersion3_2Core attribute, instead of NSOpenGLProfileVersion4_1Core. macOS will return the highest version context it can, which for modern macs is 4.1.

Other libraries for cross platform context creation, such as glfw, will use the NSOpenGLProfileVersion4_1Core attribute when requesting a 4.1 context. This leads to a failure when attempting to create a 4.1 Qt context that is shared with an externally created glfw 4.1 context.

Ideally Qt should specify the NSOpenGLProfileVersion4_1Core attribute when a 4.1 context is requested.

The issue can be worked around by requesting a 3.2 context in glfw, as it will also return a 4.1 context on the right hardware, however this solution is not ideal and is counter-intuitive.