ConfigFlags Are Not Flags

[martindevans]

The ConfigFlags enum contains flags which can be combined together like so:

var config = ConfigFlags.FLAG_WINDOW_RESIZABLE | ConfigFlags.FLAG_WINDOW_HIGHDPI
           | ConfigFlags.FLAG_MSAA_4X_HINT | ConfigFlags.FLAG_VSYNC_HINT

However doing that can trigger warning from linters:

Bitwise operation on enum that is not marked by the [Flags] attribute

To fix this, ConfigFlags should be tagged with [FlagsAttribute].

Normally I would submit a PR for this fix, but I assume it should be made in a code-gen script somewhere, not in the source itself.