Revert previous (stop building static libfb.a module for Xorg 1.10).

It breaks builds in xorg-server.old/hw/xfree86/Xorg on alpha,
netwinder, and sgimips (but not vax).

>> dependall ===> external/mit/xorg/server/xorg-server.old/hw/xfree86/Xorg
>> nbmake[13]: don't know how to make [...]/xorg-server.old/hw/xfree86/dixmods/fb/libfb.a. Stop

Stop building static libfb.a module for Xorg server 1.10 ports.

It looks unused and marked as obsolete in
src/distrib/sets/lists/xserver/md.* list files since netbsd-8.

branches: 1.1.1;
Initial revision

import the xorg-server 1.10 reach over tree as xorg-server.old.