Revert upstream "fb: Remove even/odd tile slow-pathing" changes.

https://gitlab.freedesktop.org/xorg/xserver/-/commit/e572bcc7f4236b7e0f23ab762f225b3bce37db59
>> fb: Remove even/odd tile slow-pathing
>>
>> Again, clearly meant to be a fast path, but this turns out not to be the
>> case.

This causes serious performance regression on 1bpp servers.
Ok'ed by mrg@. See my post on tech-x11@ for more details:
https://mail-index.netbsd.org/tech-x11/2020/08/07/msg002115.html

initial import of xorg-server-1.20.3

initial import of xorg-server-1.18.4

initial import of xorg-server 1.10.3. highlights include:
- fixes xorg bugs 29969, 30367, 30527, 30267, 30260, 29046,
30260, 31548, 28672, 24887, 32115, 21457, 32436, 21827,
28414, 24703, 32803, 16318, 33449, 33324, 33929, 35082,
35209, 36146, 36119
- many additional NULL checks
- adjustments related to input ABI 12
- *lots* of dead code removal
- vga arbitrator fixes
- GL fixes
- EDID fixes
- conversion to using asprintf() in many places
- many fixes from valgrind, compiler warnings

see these for more details:
http://lists.freedesktop.org/archives/xorg-announce/2011-February/001612.html
http://lists.freedesktop.org/archives/xorg-announce/2011-April/001646.html
http://lists.freedesktop.org/archives/xorg-announce/2011-May/001675.html
http://lists.freedesktop.org/archives/xorg-announce/2011-July/001710.html

import xorg-server 1.9.2. important changes since 1.6.5 include:

- built-in symbol visibility, default not export
- fixes for various crashes
- many fixes for XI2, EXA, dix, render, glx, xkb, EDID, randr, Xv,
resource handling, Xext, vfb, xfree86 / vga and composite support.
- fixes several memory leaks
- many many documentation updates
- record extension enabled
- no longer looks for XF86Config files

initial import of xorg-server-1.6.1.901

initial import of xorg-server-1.4.2