[GLX] Error generated on failure to create an indirect GLX context is unspecified

glXCreateContext, glXCreateNewContext, and glXCreateContextAttribsARB will generate an error if the "direct" argument is False but the server does does not allow indirect GLX contexts, which has been X.org's default behavior for some time. However the GLX specification does not mention what the error should be in this case. For example, Mesa's server-side GLX implementation will generate a different error than NVIDIA's.