It occurred to me that Eye of the Beholder wrote in 
gmane.os.netbsd.devel.pkgsrc.user:
> Hello.
>
> 2)
> All programs using libX11 or any other lib from xorg-libs crash with
> signal 10. I posted this in current-users and got the reply to use
> "-fno-strict-aliasing" which worked and now everything works.

Please file that PR like you've been asked to :)

> I compiled the xorg-libs in netbsd-i386 which works fine, and in
> netbsd-amd64 with a amd cpu which also works fine. It only crashes
> on netbsd-amd64 with a intel cpu.

No, it crashes for me too, and I'm using a genuine AMD.

> I don't know if anyone had this problem so it may be a patch for it.

Please send-pr so other people can benefit.

> 3) After, messing with X11PREFIX,X11ROOT_PREFIX,X11BASE

Don't. It'll come back to haunt you. xorg goes in /usr/pkg/xorg. Adding a
symlink from /usr/X11R6 is fine, though.

> I put USE_X11BASE=yes on their makefile and did installed them
> in /usr/pkg/xorg fine. 

Bad idea. This is not the intended purpose of USE_X11BASE.

> 4)
> x11/gtk installs in /usr/pkg/xorg while x11/gtk2 installs in
> /usr/pkg. Is this normal ?

This is probably related to 3). x11/gtk installs in /usr/pkg.