Xorg configure failure with Radeon card

[Dutch Ingraham]

Greetings:

I just performed a fresh install of 10.1-RELEASE #0 r274401, then
proceeded to build xorg from ports.  My video card is a Radeon 5450 and
I am attempting to set up dual-head. Upon configuring Xorg according to
6.4.2 of the Handbook, I was presented with this:

  "2160.756] (**) ModulePath set to "/usr/local/lib/xorg/modules"
[  2160.756] (WW) Hotplugging is on, devices using drivers 'kbd',
'mouse' or 'vmmouse' will be disabled.
[  2160.756] (WW) Disabling Mouse0
[  2160.756] (WW) Disabling Keyboard0
[  2160.756] (II) [KMS] No DRICreatePCIBusID symbol, no kernel modesetting.
[  2160.756] Segmentation fault at address 0x0
[  2160.756]
Fatal server error:
[  2160.756] Caught signal 11 (Segmentation fault). Server aborting
[  2160.756]
[  2160.756]
Please consult the The X.Org Foundation support"

This same "No DRICreatePCIBusID symbol, no kernel modesetting" message
followed by a segfault was addressed (but left unresolved) in this thread:

https://docs.freebsd.org/cgi/getmsg.cgi?fetch=289353+0+archive/2014/freebsd-x11/20140716.freebsd-x11

I then followed those instructions and added WITH_NEW_XORG,
WITH_GALLIUM, and WITH_KMS to my make.conf, then rebuilt, just to be
sure, all xorg packages.  Same segfault.

I also captured the compile messages for the dri package and noticed
that apparently WITH_GALLIUM is deprecated in favor of
OPTIONS_SET=GALLIUM.  I changed my make.conf to:

WITH_NEW_XORG=YES
WITH_KMS=YES
OPTIONS_SET=GALLIUM

but I am getting the same error.

Any ideas as to a resolution would be appreciated.  Thanks.