Xlib's Window changed to u64, conforming to X.h

[radgeRayden]

As per gfx-rs/wgpu-native#304. The type definition for the X Window handles can be found at https://gitlab.freedesktop.org/xorg/proto/xorgproto/-/blob/master/include/X11/X.h?ref_type=heads#L96. Window is of type XID = u64.

[kainino0x]

I found that this changed in this PR, and also was reported as a problem there:
#30 (comment)

Window is of type XID = u64.

AFAICT it can also be u32:

#ifndef _XSERVER64
#  ifndef _XTYPEDEF_XID
#    define _XTYPEDEF_XID
typedef unsigned long XID;
// ...
#else
#  include <X11/Xmd.h>
#  ifndef _XTYPEDEF_XID
#    define _XTYPEDEF_XID
typedef CARD32 XID;

where I'm pretty sure CARD32 is always uint32_t:

# ifdef LONG64
typedef unsigned long CARD64;
typedef unsigned int CARD32;
# else
typedef unsigned long long CARD64;
typedef unsigned long CARD32;
# endif

Anyway, this is a mess. I don't think we can match the type, because it requires knowing whether X was built with _XSERVER64 enabled.

The conclusion is the same, though - we need to make this a uint64_t, I think, so we can represent the handle in either case.