This patch fixes all waffle_*_get_native functions for glx, x11_egl, and
wayland. The functions never did work because I incorrectly implemented
them like this:

    union waffle_native_display*
    glx_display_get_native(...)
    {
        struct waffle_glx_display *n_dpy = malloc(sizeof(*n_dpy));
        [fill n_dpy];
        return (union waffle_native_display*) n_dpy;
    }

That implementation would have been correct if the union were defined as:

    union waffle_native_display {
        struct waffle_glx_display glx;
        ...
    };

Instead, the union is defined as:

    union waffle_native_display {
        struct waffle_glx_display *glx;
        ...
    };

Therefore, the correct implementation looks like this, modulo error
checking:

    union waffle_native_display*
    glx_display_get_native(...)
    {
        union waffle_native_display *n_dpy = malloc(sizeof(*n_dpy));
        n_dpy->glx = malloc(sizeof(*n_dpy->glx));
        [fill n_dpy->glx];
        return n_dpy;
    }

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>